Biomass gasifycation furnace and system for methanol synthesis using gas produced by gasifying biomass

ABSTRACT

Methanol is synthesized from a gas produced through gasification of biomass serving as a raw material, making use of a biomass feeding means for feeding biomass into a furnace main body and, located above the biomass feeding means, combustion-oxidizing-agent-feeding means for feeding into the furnace main body a combustion-oxidizing agent containing oxygen or a mixture of oxygen and steam.

TECHNICAL FIELD

[0001] The present invention relates to a biomass gasification furnace,and to a methanol synthesis system making use of a gas produced throughbiomass gasification.

BACKGROUND ART

[0002] The word biomass generally refers to substances of biologicalorigin (e.g., agricultural products or by-products; lumber; plants;etc.) that can be utilized as an energy source or industrial rawmaterial. Since biomass is produced by solar energy, and by the actionof air, water, soil, or similar natural substances, it can be producedinfinitely.

[0003] Fuel, methanol, and similar materials can be produced making useof the above-described biomass. Also, since biomass that exists in theform of waste can be utilized, a clean environment can be provided.Further, since newly produced biomass is grown through photosynthesis;i.e., fixation of CO₂, the concentration of CO₂ in the atmosphere is notincreased.

[0004] Conventionally proposed methods for converting biomass intoalcohol include, for example, the fermentation method and thehydrothermal degradation method. The former method, the fermentationmethod, requires installation of a tank for sugar components, whereasthe hydrothermal degradation method involves the problems that hightemperature and high pressure are required and yet yield is low.Moreover, another problem is that, considerable amounts of residue aregenerated from the input biomass, raising the problem of low biomassutilization.

[0005] Meanwhile, in the case in which biomass is gasified, agasification furnace, such as a fixed-bed gasification furnace or afluidized-bed gasification furnace, has heretofore been employed.However, since only the surface portions of granular biomass undergoreaction, and the reaction cannot proceed uniformly to the innermostportion of the granules, tar is generated, and the produced gas; i.e.,the gas obtained through gasification, has a low H₂ content and low COcontent. Therefore, the thus-produced gas cannot serve as a raw materialfor methanol synthesis. Moreover, the generated tar is deposited notonly onto the inside wall of the furnace, but also onto the apparatuses,etc. installed on the downstream side of the furnace, invitingproblematic maloperation of the furnace.

[0006] In order to prevent such problems, conventionally, oxygen issupplied in great amounts so as to effect combustion at hightemperature. However, in this case, another problem is involved; ahigh-temperature zone of higher than 1,200° C. is formed at someportions, where gasification of biomass does not proceed successfully,providing large amounts of soot through combustion of biomass.

[0007] In view of the foregoing, an object of the present invention isto provide a biomass gasification furnace which promises clean,high-efficiency gasification, which contemplates complete gasificationof biomass, and which is capable of producing a gas realizing a highlyefficient methanol synthesis. Another object of the present invention isto provide a methanol synthesis system making use of the thus-producedgas.

DISCLOSURE OF THE INVENTION

[0008] A variety of modes of the gasification furnace of the presentinvention making use of biomass as a raw material will next bedescribed.

[0009] A first mode is drawn to a biomass gasification furnace employingbiomass as a raw material, characterized in that said furnace comprisesmeans for feeding pulverized biomass having an average particle size (D)falling within a range of 0.05≦D≦5 mm andcombustion-oxidizing-agent-feeding means for feeding oxygen or a mixtureof oxygen and steam serving as a combustion-oxidizing agent, and thatgasification conditions include a furnace interior temperature of700-1,200° C.

[0010] A second mode is drawn to a biomass gasification furnace inrelation to the first mode, wherein the mol ratio of oxygen [O₂]/carbon[C] in the biomass gasification furnace falls within a range of0.1≦O₂/C<1.0, and the mol ratio of steam [H₂O]/carbon [C] falls within arange of 1≦H₂O/C.

[0011] A third mode is drawn to a biomass gasification furnace inrelation to the first mode, wherein the internal pressure of the biomassgasification furnace is 1-30 atm, and gasification conditions include asuperficial velocity of 0.1-5 m/s.

[0012] A fourth mode is drawn to a biomass gasification furnace inrelation to the first mode, wherein the combustion-oxidizing agent isfed to a plurality of stages in the biomass gasification furnace.

[0013] A fifth mode is drawn to a biomass gasification furnace inrelation to the first mode, wherein fossil fuel is fed into the biomassgasification furnace.

[0014] In the fifth mode, the fossil fuel may be coal.

[0015] A sixth mode is drawn to a biomass gasification furnace inrelation to the first mode, wherein the biomass gasification furnacecomprises a gas-purification unit for purifying a gas formed throughgasification carried out in the biomass gasification furnace; andbiomass and a combustion-oxidizing agent are fed such that thecompositional ratio H₂/CO of the generated gas approaches 2.

[0016] A seventh mode is drawn to a biomass gasification furnace inrelation to the sixth mode, wherein the amount of oxygen derived fromthe combustion-oxidizing agent is such that heat generated duringpartial oxidation of biomass exceeds the heat that has been absorbedduring decomposition of biomass.

[0017] In the above mode, the combustion-oxidizing agent may have anoxygen content of 3-15%.

[0018] An eighth mode is drawn to a biomass gasification furnace inrelation to the sixth mode, wherein steam serving as thecombustion-oxidizing agent is high-temperature steam of at least 300° C.

[0019] In the above mode, the high-temperature steam may be obtainedthrough heat exchange with gas generated through gasification.

[0020] A ninth mode is drawn to a biomass gasification furnace inrelation to the sixth mode, further comprising steam reforming meansprovided in the vicinity of an upper outlet of the biomass gasificationfurnace or on the downstream side of the gasification furnace.

[0021] In the above-described mode, the steam reforming means may reformthe hydrocarbon contained in the produced gas into CO and H₂ by use of anickel catalyst.

[0022] In the above mode, the steam reforming may be performed at 500°C. or higher.

[0023] A tenth mode is drawn to a biomass gasification furnace inrelation to the first mode, wherein the biomass gsification furnacefurther comprises feeding means for feeding biomass provided at a topsection of a gasification furnace main body, and an ash receivingsection provided in a bottom section of the gasification furnace mainbody.

[0024] An eleventh mode is drawn to a biomass gasification furnace inrelation to the tenth mode, wherein the biomass gasification furnacefurther comprises a gas discharge tube provided at a lower portion of aside wall of the gasification furnace main body so as to discharge gasproduced through gasification.

[0025] A twelfth mode is drawn to a biomass gasification furnace inrelation to the tenth mode, wherein the biomass gasification furnacefurther comprises hollow cylindrical gas-ash introducing means having adownwardly reduced diameter and provided on an inner wall surface of thegasification furnace in the vicinity of the upper section of the gasdischarge tube of the gasification furnace.

[0026] A thirteenth mode is drawn to a biomass gasification furnace inrelation to the eleventh mode, wherein the biomass gasification furnacefurther comprises cooling means on the side wall of the gasificationfurnace main body, and at least one soot removing means for blowing outdeposits adhering onto an inner wall surface of the gasificationfurnace.

[0027] A fourteenth mode is drawn to a biomass gasification furnace inrelation to the twelfth mode, wherein the biomass gasification furnacefurther comprises a water bath section provided at a bottom section ofthe biomass gasification furnace, and hollow cylindrical gas-ashintroducing means having a downwardly reduced diameter, the end portionof the introducing means being dipped in the water bath section.

[0028] A fifteenth mode is drawn to a biomass gasification furnace inrelation to the tenth mode, wherein the biomass gasification furnacefurther comprises a gas discharge tube for discharging produced gasprovided at the center of the top section of the biomass gasificationfurnace, the gas discharge tube extending vertically such that a lowerend portion of a predetermined length of the gas discharge tube isinserted into the interior of the gasification furnace with thelower-end opening of the gas discharge tube facing the interior of thefurnace.

[0029] A sixteenth mode is drawn to a biomass gasification furnace inrelation to the fifteenth mode, wherein the bottom section of thegasification furnace main body has a hollow cylindrical shape ofdownwardly reduced diameter, and the gasification furnace furthercomprises a water bath section provided at a bottom section thereof.

[0030] A seventeenth mode is drawn to a biomass gasification furnace inrelation to the tenth mode, wherein the diameter of a lower half portionof the gasification furnace main body is slightly reduced as comparedwith the diameter of an upper half portion of the main body; a partitionis provided vertically in the interior of the diameter-reduced portionof the gasification furnace main body, thereby forming a path forintroducing produced gas and ash; the produced gas and ash are caused topass through the path; and the produced gas is forced to turn at thefrontal edge of the partition, thereby removing the ash and dischargingthe produced gas from the gas discharge tube for discharging theproduced gas.

[0031] An eighteenth mode is drawn to a biomass gasification furnace inrelation to the seventeenth mode, wherein the biomass gasificationfurnace further comprises a heat exchanger provided in theabove-mentioned path so as to perform heat exchange with produced gas.

[0032] A nineteenth mode is drawn to a biomass gasification furnacecombusting biomass so as to generate combustion gas and to gasifybiomass by use of the combustion gas as a heat source, characterized inthat a combustion space for combusting the biomass and a gasificationspace for gasifying the biomass are separated from each other; and acombustion gas feeding line for feeding, into the gasification space,the combustion gas generated in the combustion space is provided betweenthe combustion space and the gasification space.

[0033] A twentieth mode is drawn to a biomass gasification furnace inrelation to the nineteenth mode, wherein the combustion space and thegasification space are provided in separately disposed combustion andgasification chambers, respectively; a reaction tube is provided in thegasification chamber; the gasification space is provided in the reactiontube; a combustion gas feeding passage connected to the combustion gasfeeding line is provided between the inside wall surface of thegasification chamber and the outside wall surface of the reaction tube;and perforations for uniformly feeding the combustion gas from thecombustion gas feeding passage to the reaction tube are provided in thereaction tube.

[0034] A twenty-first mode is drawn to a biomass gasification furnace inrelation to the nineteenth mode, wherein the combustion space and thegasification space are provided in separately disposed combustion andgasification chambers, respectively; a reaction tube is provided in thegasification chamber; the gasification space is provided in the reactiontube; and a combustion gas feeding passage connected to the combustiongas feeding line is provided between the inside wall surface of thegasification chamber and the outside wall surface of the reaction tube.

[0035] A twenty-second mode is drawn to a biomass gasification furnacein relation to the nineteenth mode, wherein the combustion space and thegasification space are provided in a single chamber in such a mannerthat the combustion space and the gasification space are separated fromeach other; a reaction tube is provided in the single chamber; thegasification space is provided in the reaction tube; a combustion gasfeeding passage connected to the combustion gas feeding line is providedbetween the inside wall surface of the chamber and the outside wallsurface of the reaction tube; and perforations for uniformly feeding thecombustion gas from the combustion gas feeding passage to the reactiontube are provided in the reaction tube.

[0036] A twenty-third mode is drawn to a biomass gasification furnace inrelation to the twentieth mode, wherein a line for feeding steam so asto prevent carbon formation and soot formation is provided in thecombustion space.

[0037] A twenty-fourth mode is drawn to a biomass gasification furnacein relation to the twenty-first mode, wherein a line for feeding steamfrom which oxygen has been removed is provided in the gasificationspace.

[0038] A twenty-fifth mode is drawn to a biomass gasification furnace inrelation to the twentieth mode, wherein heat recovery means and/or dustprevention means is provided in the combustion space.

[0039] A twenty-sixth mode is drawn to a biomass gasification furnace inrelation to the twentieth mode, wherein a combustion gas exhaust line isprovided in the combustion gas feeding passage and heat recovery meansis provided in the combustion gas exhaust line.

[0040] A twenty-seventh mode is drawn to a biomass gasification furnacein relation to the twentieth mode, wherein a combustion gas exhaust lineis provided in the combustion gas feeding passage, and means forrecovering unreacted biomass for gasification is provided between thecombustion gas exhaust line and the reaction tube.

[0041] A twenty-eighth mode is drawn to a biomass gasification furnacein relation to the twentieth mode, wherein a produced-gas exhaust lineis provided in the gasification space and heat recovery means isprovided in the produced-gas exhaust line.

[0042] A twenty-ninth mode is drawn to a biomass gasification furnace inrelation to the twentieth mode, wherein the combustion chamber has anopening for feeding biomass for combustion, and the opening is providedwith an opening and closing cap attached thereto such that the openingcan be opened and closed.

[0043] A variety of modes for carrying out the gasification method ofthe present invention employing biomass as a raw material will next bedescribed.

[0044] A thirtieth mode is drawn to a biomass gasification methodemploying biomass as a raw material, characterized by comprisingfeeding, to a biomass gasification furnace, pulverized biomass having anaverage particle size (D) falling within a range of 0.05≦D≦5 mm and amixture of air and steam or a mixture of oxygen and steam serving as acombustion-oxidizing agent; and employing gasification conditionsincluding a mol ratio of oxygen [O₂]/carbon [C] falling within a rangeof 0.1≦O₂/C<1.0, a mol ratio of steam [H₂O]/carbon [C] falling within arange of 1≦H₂O/C, and a furnace interior temperature of 700-1,200° C.

[0045] A thirty-first mode is drawn to a biomass gasification method inrelation to the thirtieth mode, wherein the internal pressure of thebiomass gasification furnace is 1-30 atm, and gasification conditionsinclude a superficial velocity of 0.1-5 m/s.

[0046] A thirty-second mode is drawn to a biomass gasification method inrelation to the thirtieth mode, wherein the combustion-oxidizing agentis fed to a plurality of stages in the biomass gasification furnace.

[0047] A thirty-third mode is drawn to a biomass gasification systemcharacterized by comprising a gas purification unit for purifying gasgenerated through gasification performed in the biomass gasificationfurnace as recited in relation to the first mode and a gas turbineemploying the resultant purified gas as a fuel.

[0048] A thirty-fourth mode is drawn to a biomass gasification methodcharacterized in that a portion of biomass is combusted through partialcombustion; the temperature of the interior of the gasification furnaceis elevated by effectively utilizing heat of CO₂ produced during thecourse of chemical synthesis; and biomass is gasified whilehigh-temperature steam is supplied.

[0049] A thirty-fifth mode is drawn to a biomass gasification method inrelation to the thirty-fourth mode, wherein the hydrocarbon contained inthe produced gas is steam-reformed to form CO and H₂, to thereby controlthe compositional ratio H₂/CO of the gas to approximately 2.

[0050] A variety of modes of the methanol synthesis system of thepresent invention employing biomass as a raw material will next bedescribed.

[0051] A thirty-sixth mode is drawn to a methanol synthesis systemcharacterized by comprising a gas purification unit for purifying gasgenerated through gasification performed in the biomass gasificationfurnace as recited in relation to the first mode, and a methanolsynthesis unit for synthesizing methanol from H₂ and CO contained in theresultant purified gas.

[0052] A thirty-seventh mode is drawn to a methanol synthesis system inrelation to the thirty-sixth mode, further comprising, on the upstreamside of the methanol synthesis unit, a CO shift reaction unit foradjusting the compositional ratio of H₂ to CO gas contained in a gas.

[0053] A thirty-eighth mode is drawn to a methanol synthesis system inrelation to the thirty-sixth mode, further comprising a carbon dioxideremoval unit provided on the upstream side of the methanol synthesisunit.

[0054] In the above-described mode, carbon dioxide gas which hasundergone removal of excess carbon dioxide may be employed as a carriergas for feeding biomass into the biomass gasification furnace.

[0055] In the above-described mode, a discharge gas which has undergonerecovery of methanol may be employed as a carrier gas for feedingbiomass into the biomass gasification furnace.

[0056] In the above-described mode, a discharge gas which has undergonerecovery of methanol may be fed into the biomass gasification furnace.

[0057] A thirty-ninth mode is drawn to a methanol synthesis systemmaking use of biomass, characterized by comprising a gasificationfurnace as described in relation to the sixth mode, heat exchangingmeans for removing steam contained in purified gas, and a methanolsynthesis unit for synthesizing methanol from cooled gas which hasundergone heat exchange.

[0058] A fortieth mode is drawn to a methanol synthesis system makinguse of biomass, the system being as described in relation to thethirty-ninth mode, further comprising a carbon dioxide removal unit,provided on an upstream side of the methanol synthesis unit, forremoving CO₂ in produced gas.

[0059] A forty-first mode is drawn to a methanol synthesis system makinguse of biomass, comprising a gasification furnace as recited in relationto the sixth mode; heat exchanging means for removing steam contained inpurified gas; a methanol synthesis unit for synthesizing methanol fromcooled gas which has undergone heat exchange, and a CO shift reactionunit for adjusting the compositional ratio of H₂ to CO gas contained inthe purified gas.

[0060] A forty-second mode is drawn to a methanol synthesis systemmaking use of biomass, the system being as described in relation to theforty-first mode, further comprising, on an upstream side of themethanol synthesis unit, a carbon dioxide removal unit for removing CO₂in produced gas.

[0061] In the above-described mode, CO₂ from which excess carbon dioxidehas been removed may be employed as a carrier gas for feeding biomassinto the biomass gasification furnace.

[0062] In the above-described mode, the humidity and temperature ofoxygen to be fed into the biomass gasification furnace may be elevatedby use of water removed by the heat exchanging means.

[0063] In the above-described mode, a discharge gas which has undergonerecovery of methanol may be employed as a carrier gas for feedingbiomass into the biomass gasification furnace.

[0064] In the above-described mode, a discharge gas which has undergonerecovery of methanol may be fed into the biomass gasification furnace.

[0065] In the above-described mode, a discharge gas which has undergonerecovery of methanol may be employed as a fuel for a gas engine.

[0066] In the above-described mode, heat generated and recovered duringproduction of methanol may be used in a gas turbine.

[0067] In the above-described mode, heat generated and recovered duringproduction of methanol may be used for drying biomass.

[0068] A forty-third mode is drawn to a methanol synthesis system,wherein a biomass gasification system of the thirty-ninth mode ismounted on a base so as to allow conveyance of the system.

[0069] A forty-fourth mode is drawn to a methanol synthesis system,wherein a biomass gasification system of the thirty-ninth mode ismounted on a traveling carriage so as to enable transport of the system.

[0070] A forty-fifth mode is drawn to a methanol synthesis system makinguse of biomass, the system being as described in relation to theforty-first mode, wherein discharge water from the heat exchanging meansis introduced into the methanol synthesis unit, so as to recover heatgenerated during the course of methanol synthesis, and subsequently, theheated water is introduced into the cooling means, to thereby recoverheat from the produced gas, and the thus-obtained heated steam is fedinto the biomass gasification furnace.

[0071] A forty-sixth mode is drawn to a methanol synthesis system makinguse of biomass, the system being as described in relation to theforty-fifth mode, wherein the heat exchanging means comprises watersprinkling means and alkaline water sprinkling means, and the dischargewater after water sprinkling is used for recovering heat.

[0072] A forty-seventh mode is drawn to a methanol synthesis systemmaking use of biomass, the system being as described in relation to theforty-fifth mode, further comprising an adsorption column or a guardcolumn inserted between a booster unit and a regenerator and/or betweenthe regenerator and the methanol synthesis unit.

[0073] A forty-eighth mode is drawn to a methanol synthesis systemmaking use of biomass, the system being as described in relation to theforty-fifth mode, wherein a gas generated from the methanol synthesisunit is subjected to gas-liquid separation; H₂ contained in theseparated gas is removed by means of a hydrogen separation unit; and theremoved H₂ is fed back to a site on the upstream side of theregenerator.

[0074] A forty-ninth mode is drawn to a methanol synthesis system makinguse of biomass, the system being as described in relation to theforty-fifth mode, wherein the methanol synthesis unit is a synthesiscolumn comprising a plurality of stages of catalyst layers, and at leasttwo series of the synthesis columns are provided.

[0075] A fiftieth mode is drawn to a methanol synthesis system makinguse of biomass, the system being as described in relation to theforty-ninth mode, wherein the catalyst layer placed on an inlet side ofthe synthesis column serves as a guard column.

[0076] A variety of modes of the methanol synthesis method making use ofbiomass serving as a raw material will next be described.

[0077] A fifty-first mode is drawn to a methanol synthesis method makinguse of biomass characterized by synthesizing methanol through removal ofCO₂ contained in the gas obtained through the gasification method of thethirty-fourth mode.

[0078] A fifty-second mode is drawn to a methanol synthesis methodmaking use of biomass, characterized by adjusting, by means of a COshift reaction unit, the compositional ratio of H₂ to CO gas of a gasobtained through the gasification method of the thirty-fourth mode, tothereby regulate the compositional ratio H₂/CO of the gas toapproximately 2.

[0079] In the above-described mode, CO₂ from which excess carbon dioxidehas been removed may be employed as a carrier gas for feeding biomassinto the biomass gasification furnace.

[0080] In the above-described mode, a discharge gas which has undergonerecovery of methanol may be employed as a carrier gas for feedingbiomass into the biomass gasification furnace.

[0081] In the above-described mode, a discharge gas which has undergonerecovery of methanol may be fed to the biomass gasification furnace.

[0082] In the above-described mode, a discharge gas which has undergonerecovery of methanol may be employed as a fuel for a gas engine.

[0083] A fifty-third mode is drawn to a methanol synthesis method makinguse of biomass, the method being as recited in relation to thefifty-first mode, wherein heat generated and recovered during the courseof production of methanol is used in a gas turbine.

[0084] A fifty-fourth mode is drawn to a methanol synthesis methodmaking use of biomass, the method being as recited in relation to thefifty-first mode, wherein the recovered heat generated during the courseof production of methanol is utilized for drying biomass.

[0085] A fifty-fifth mode is drawn to a methanol synthesis method makinguse of biomass, characterized in that, by employing the methanolsynthesis system of the forty-ninth mode, a first synthesis column and asecond synthesis column are used alternately during synthesis ofmethanol, and that when one synthesis column is in use, among aplurality of stages of catalyst layers in the other synthesis column,the first-stage catalyst layer on a gas inlet side is removed, thesecond-stage catalyst layer is caused to serve as the first-stage layer,and a new additional catalyst layer is inserted so as to be placed atthe position of the final stage.

[0086] A variety of modes of the coal gasification method of the presentinvention making use of biomass as a raw material will next bedescribed.

[0087] A fifty-sixth mode is drawn to a coal gasification methodcharacterized by comprising feeding biomass to a reductor of a coalgasification furnace including a combustor and the reductor or to a siteon the downstream side of the reductor, and effecting gasification ofcoal and the biomass simultaneously.

[0088] A fifty-seventh mode is drawn to a coal gasification method asdescribed in relation to the fifty-sixth mode, wherein the biomass isfed after being mixed with coal in advance.

[0089] A fifty-eighth mode is drawn to a coal gasification method asdescribed in relation to the fifty-sixth mode, wherein the biomass andcoal are fed through positions which face each other.

[0090] A fifty-ninth mode is drawn to a coal gasification method asdescribed in relation to the fifty-seventh mode, wherein the biomass isfed through a position on a downstream side of a position through whichthe coal is fed.

[0091] A methanol synthesis system by employment of coal gasificationmaking use of biomass as a raw material will next be described.

[0092] A sixtieth mode is drawn to a methanol synthesis system makinguse of biomass, characterized by comprising a gas purification unit forpurifying a gas produced through the gasification method of thefifty-sixth mode, and a methanol synthesis unit for synthesizingmethanol from the gas which has been purified.

[0093] A sixty-first mode is drawn to a methanol synthesis system makinguse of biomass, the system being as described in relation to thesixtieth mode, further comprising a steam reforming means for reforminghydrocarbons contained in the produced gas into CO and H₂, the reformingmeans being provided within a gasification furnace or at the outlet ofthe gasification furnace.

[0094] A sixty-second mode is drawn to a methanol synthesis systemmaking use of biomass in relation to the sixtieth mode, furthercomprising a CO shift reaction unit for regulating the compositionalratio of H₂ to CO gas contained in the purified gas.

[0095] A sixty-third mode is drawn to a methanol synthesis system makinguse of biomass in relation to the sixtieth mode, further comprising, onthe upstream side of the methanol synthesis unit, a carbon dioxideremoving unit for removing CO₂ in the produced gas.

[0096] A sixty-fourth mode is drawn to a methanol synthesis systemincluding a biomass gasification furnace employing a gas producedthrough combustion of biomass serving as a heat source for gasifyingbiomass and a methanol synthesis unit employing, for synthesizingmethanol, a synthesis gas produced in the above-described biomassgasification furnace, characterized in that the biomass gasificationfurnace comprises a combustion space for combusting the biomass and agasification space for gasifying the biomass, the spaces being providedseparately, and a combustion gas feeding line for feeding the combustiongas from the combustion space to the gasification space is providedbetween the combustion space and the gasification space; and themethanol synthesis unit comprises a pressurizing chamber, a catalystchamber, and a methanol recovery chamber, and operates such that thesynthesis gas introduced from the biomass gasification furnace into thepressurizing chamber, the catalyst chamber, and the methanol recoverychamber is pressurized at a predetermined pressure, to thereby transformthe synthesis gas into methanol through catalytic reaction in thecatalyst chamber, the methanol is liquefied in the methanol recoverychamber, and the liquefied methanol is recovered and the residual gas ispurged.

[0097] A sixty-fifth mode is drawn to a methanol synthesis systemincluding a biomass gasification furnace, the system being as describedin relation to the sixty-fourth mode, further comprising a storage tankfor storing the synthesis gas from the biomass gasification furnace—thegas being stored therein during introduction of the synthesis gas, andsynthesis, liquefaction, and recovery of methanol in the methanolsynthesis unit of batch-type—between the biomass gasification furnaceand the methanol synthesis unit.

[0098] A sixty-sixth mode is drawn to a methanol synthesis systemincluding a biomass gasification furnace, the system being as describedin relation to the sixty-fourth mode, wherein the catalyst chambercomprises heating means.

[0099] A sixty-seventh mode is drawn to a methanol synthesis systemincluding a biomass gasification furnace, the system being as describedin relation to the sixty-fourth mode, the methanol recovery chambercomprises cooling means.

[0100] A sixty-eighth mode is drawn to a methanol synthesis systemincluding a biomass gasification furnace for producing a synthesis gasthrough combustion and thermal decomposition of biomass and a methanolsynthesis unit for synthesizing methanol from the synthesis gas producedin the biomass gasification furnace. characterized in that the methanolsynthesis unit comprises a pressurizing chamber, a catalyst chamber, anda methanol recovery chamber, and operates such that the synthesis gasintroduced from the biomass gasification furnace into the pressurizingchamber, the catalyst chamber, and the methanol recovery chamber ispressurized at a predetermined pressure, the synthesis gas istransformed into methanol through catalytic reaction in the catalystchamber, the methanol is liquefied in the methanol recovery chamber, andthe liquefied methanol is recovered and the residual gas is purged.

[0101] A variety of modes for feeding biomass into a biomassgasification furnace of the present invention will next be described.

[0102] A sixty-ninth mode is drawn to a biomass feeding unit, whichserves as feeding means for feeding biomass into a biomass gasificationfurnace, characterized by comprising a hollow cylindrical hopper forstoring granular material, such as fibrous granular biomass obtained byfinely pulverizing biomass, and a screw feeder disposed at a lowerportion of the hopper and adapted to convey the granular material in ahorizontal direction and to discharge the granular material to theoutside through an outlet which is provided at the distal end portion ofa casing of the screw feeder such that the outlet is opened downward,wherein the feeding unit further comprises stirring means for stirringthe granular material contained in the hopper such that the granularmaterial stored in the hopper is fed to the screw feeder.

[0103] A seventieth mode is drawn to a biomass feeding unit, whichserves as feeding means for feeding biomass into a biomass gasificationfurnace, characterized by comprising a hollow cylindrical hopper forstoring granular material, such as fibrous granular biomass obtained byfinely pulverizing biomass, and a screw feeder disposed at a lowerportion of the hopper and adapted to convey the granular material in ahorizontal direction and to discharge the granular material to theoutside through an outlet which is provided at the distal end portion ofa casing of the screw feeder such that the outlet is opened downward,wherein the feeding unit further comprises stirring means for stirringthe granular material contained in the hopper such that the granularmaterial stored in the hopper is fed to the screw feeder; and on theside on which the base end portion of the screw feeder is present, theoutlet provided at the distal end potion of the casing has a side of astraight line crossing the axis of the screw feeder.

[0104] A seventy-first mode is drawn to a biomass feeding unit asdescribed in relation to the seventieth mode, wherein the straight linecrosses the axial direction of the screw feeder at the right angle.

[0105] A seventy-second mode is drawn to a biomass feeding unit asdescribed in relation to the seventieth mode, wherein the straight lineis inclined in a direction opposite to the inclination direction of ascrew flight of the screw feeder, with respect to a straight line whichcrosses the axial direction of the screw feeder at the right angle, andthe inclination angle of the straight line is identical to the anglebetween the screw flight and the straight line which crosses the axialdirection of the screw feeder at the right angle.

[0106] A seventy-third mode is drawn to a biomass feeding unit asdescribed in relation to the seventieth mode, wherein a large-diameterportion having a size larger than that of the remaining portion isprovided at the distal end portion of the casing along the axialdirection of the screw feeder, and an outlet is provided on a lowersurface of the large-diameter portion.

[0107] A seventy-fourth mode is drawn to a biomass feeding unit asdescribed in relation to the seventieth mode, wherein a plurality ofinjection nozzles are radially provided at the distal end portion of thecasing, and gas is injected through the nozzles to the granular materialwhich has arrived as conveyed through the screw feeder while beingcompressed and constrained between adjacent walls of the screw flight ofthe screw feeder, to thereby eliminate compression and entanglement ofthe granular material and discharge the granular material downwardthrough the outlet.

[0108] A seventy-fifth mode is drawn to a biomass feeding unit asdescribed in relation to the seventieth mode, wherein a screw shaft ofthe screw feeder is formed of a hollow member, and a perforationpenetrating the screw shaft from the outer circumferential surface tothe interior thereof, or an injection nozzle utilizing the perforation,is provided between adjacent walls of the screw flight in the vicinityof the distal end portion of the screw feeder, and gas is injectedthrough the perforation or injection nozzle to the granular materialwhich has arrived as conveyed through the screw feeder while beingcompressed and constrained between adjacent walls of the screw flight ofthe screw feeder, to thereby eliminate compression and entanglement ofthe granular material and discharge the granular material downwardthrough the outlet.

[0109] A seventy-sixth mode is drawn to a biomass feeding unit asdescribed in relation to the seventieth mode, further comprising afluidization cone for receiving the granular material discharged andfalling through the outlet, and imparting a gyratory flow to thegranular material to thereby eliminate entanglement of the granularmaterial, and gas forming the gyratory flow is utilized as a carrier gasfor feeding the granular material to a destination apparatus such as agasification furnace.

[0110] A seventy-seventh mode is drawn to a biomass feeding unit asdescribed in relation to the seventy-sixth mode, wherein thefluidization cone comprises stirring means for stirring the granularmaterial received by the cone.

[0111] A seventy-eighth mode is drawn to a biomass feeding unit asdescribed in relation to the seventy-fourth mode, further comprising afunnel-shaped portion for receiving the granular material discharged andfalling through the outlet, in which the path of the granular materialis gradually narrowed, and the granular material is introduced to afeeding line connected to a destination apparatus to which the granularmaterial is fowarded, such as a gasification furnace, and a carrier gasfor the granular material is supplied.

[0112] A seventy-ninth mode is drawn to a biomass feeding unit asdescribed in relation to the seventieth mode, wherein relatively largepitches are provided between adjacent walls of the screw flight at thedistal end portion of the screw shaft of the screw feeder, andrelatively small pitches are provided between adjacent walls of thescrew flight at the central portion of the screw shaft, which centralportion is adjacent to the distal end portion.

[0113] An eightieth mode is drawn to a biomass feeding unit as describedin relation to the seventieth mode, wherein pitches between adjacentwalls of the screw flight of the screw shaft of the screw feeder aregradually reduced from the base portion on the hopper side to anintermediate portion at which the pitches are minimum, and the pitchesare gradually increased from the intermediate portion to the distal endportion.

[0114] An eighty-first mode is drawn to a biomass feeding unitcharacterized by comprising a hollow cylindrical hopper for storinggranular material such as fibrous granular biomass obtained by finelypulverizing biomass, the hopper including stirring means for stirringthe granular material; and a screw feeder for conveying the granularmaterial in a horizontal direction, the feeder being provided at thelower portion of the hopper, wherein the diameter of the distal endportion of the screw feeder is gradually reduced and the distal endthereof is connected to a feeding line having a small diameter; and gasis injected, at the distal end portion of the screw feeder, to thegranular material which is compressed by and conveyed through the screwfeeder, to thereby loosen compression and eliminate entanglement ofparticles of the granular material, and the resultant granular materialis conveyed and fed, through the feeding line, by a carrier gas streamof the aforementioned gas to a destination apparatus such as agasification furnace.

[0115] An eighty-second mode is drawn to a biomass feeding unit asdescribed in relation to the eighty-first mode, wherein the gas forloosening compression and eliminating entanglement of the granularmaterial and making a carrier gas stream is fed through a perforation oran injection nozzle utilizing the perforation which penetrates the screwshaft of the screw feeder and is provided between adjacent walls of ascrew flight in the vicinity of the endmost portion of the screw shaftof the screw feeder formed of a hollow member.

[0116] An eighty-third mode is drawn to a biomass feeding unit asdescribed in relation to the eighty-first mode, wherein the gas forloosening compression and eliminating entanglement of the granularbiomass and making a carrier gas stream is fed through a plurality ofinjection nozzles radially provided at the distal end portion of acasing.

[0117] An eighty-fourth mode is drawn to a biomass feeding unit asdescribed in relation to the eighty-first mode, wherein relatively largepitches are provided between adjacent walls of the screw flight at thedistal end portion of the screw shaft of the screw feeder, andrelatively small pitches are provided between adjacent walls of thescrew flight at the central portion of the screw shaft, which centralportion is adjacent to the distal end portion.

[0118] An eighty-fifth mode is drawn to a biomass feeding unit asdescribed in relation to the eighty-first mode, wherein pitches betweenadjacent walls of the screw flight of the screw shaft of the screwfeeder are gradually reduced from the base portion on the hopper side toan intermediate portion at which the pitches are minimum, and thepitches are gradually increased from the intermediate portion to thedistal end portion.

BRIEF DESCRIPTION OF THE DRAWINGS

[0119]FIG. 1 is a schematic diagram of a methanol synthesis systememploying a biomass gasification furnace according to the firstembodiment.

[0120]FIG. 2 is a schematic diagram of a methanol synthesis systememploying a biomass gasification furnace according to the secondembodiment.

[0121]FIG. 3 is a schematic diagram of a methanol synthesis systememploying a biomass gasification furnace according to the thirdembodiment.

[0122]FIG. 4 is a schematic diagram of a methanol synthesis systememploying a biomass gasification furnace according to the fourthembodiment.

[0123]FIG. 5 is a schematic diagram of a methanol synthesis systememploying a biomass gasification furnace according to the fifthembodiment.

[0124]FIG. 6 Is a schematic diagram of a methanol synthesis systememploying a biomass gasification furnace according to the sixthembodiment.

[0125]FIG. 7 is a schematic diagram of a methanol synthesis systememploying a biomass gasification furnace according to the seventhembodiment.

[0126]FIG. 8 is a schematic diagram of a methanol synthesis systememploying a biomass gasification furnace according to the eighthembodiment.

[0127]FIG. 9 is a schematic diagram of a methanol synthesis systememploying a biomass gasification furnace according to the ninthembodiment.

[0128]FIG. 10 is a schematic diagram of a methanol synthesis systememploying a biomass gasification furnace according to the tenthembodiment.

[0129]FIG. 11 is a schematic diagram of a methanol synthesis systememploying a biomass gasification furnace according to the eleventhembodiment.

[0130]FIG. 12 is a schematic diagram of a methanol synthesis systememploying a biomass gasification furnace according to the twelfthembodiment.

[0131]FIG. 13 is a schematic diagram of a methanol synthesis systememploying a biomass gasification furnace according to the thirteenthembodiment.

[0132]FIG. 14 is an enlarged view of the relevant portion of FIG. 13.

[0133]FIG. 15 is a schematic diagram of a biomass gasification furnaceaccording to the fourteenth embodiment.

[0134]FIG. 16 is a schematic diagram of a biomass gasification furnaceaccording to the fifteenth embodiment.

[0135]FIG. 17 is a schematic diagram of a biomass gasification furnaceaccording to the sixteenth embodiment.

[0136]FIG. 18 is a schematic diagram of a biomass gasification furnaceaccording to the seventeenth embodiment.

[0137]FIG. 19 is a schematic diagram of a biomass gasification furnaceaccording to the eighteenth embodiment.

[0138]FIG. 20 is a schematic diagram of an alternative gasificationfurnace according to the eighteenth embodiment.

[0139]FIG. 21 is a schematic diagram of a biomass gasification furnaceaccording to the nineteenth embodiment.

[0140]FIG. 22 is a schematic diagram of the biomass gasification furnaceaccording to the twentieth embodiment.

[0141]FIG. 23 is a schematic diagram of a biomass gasification furnaceaccording to the twenty-first embodiment.

[0142]FIG. 24 is a schematic diagram of a biomass gasification furnaceaccording to the twenty-second embodiment.

[0143]FIG. 25 is a schematic diagram of a conventional coal gasificationfurnace.

[0144]FIG. 26 is a schematic diagram of a coal gasification furnaceaccording to the twenty-third embodiment.

[0145]FIG. 27 is a schematic diagram illustrating a method for feedingcoal micropowder and biomass according to the twenty-third embodiment.

[0146]FIG. 28 is a schematic diagram illustrating an alternative methodfor feeding coal micropowder and biomass according to the twenty-thirdembodiment.

[0147]FIG. 29 is a schematic diagram of feeding tubes for feeding coalmicropowder and biomass according to the twenty-third embodiment.

[0148]FIG. 30 is a schematic diagram of an alternative coal gasificationfurnace according to the twenty-third embodiment.

[0149]FIG. 31 is a schematic diagram of a methanol synthesis systememploying a coal gasification furnace according to the twenty-thirdembodiment.

[0150]FIG. 32 is a schematic diagram of a methanol synthesis systememploying a coal gasification furnace according to the twenty-fourthembodiment.

[0151]FIG. 33 is a schematic diagram of a methanol synthesis systememploying a coal gasification furnace according to the twenty-fifthembodiment.

[0152]FIG. 34 is a schematic diagram of a biomass gasification furnaceaccording to the twenty-sixth embodiment.

[0153]FIG. 35 is a schematic diagram of a biomass gasification furnaceaccording to the twenty-seventh embodiment.

[0154]FIG. 36 is a schematic diagram of a biomass gasification furnaceaccording to the twenty-eighth embodiment.

[0155]FIG. 37 is a schematic diagram showing a methanol synthesis systemequipped with a biomass gasification furnace according to thetwenty-ninth embodiment.

[0156]FIG. 38 is a schematic diagram of a biomass gasification furnaceaccording to the twenty-ninth embodiment.

[0157]FIG. 39 is a schematic diagram of a methanol synthesis unitaccording to the twenty-ninth embodiment.

[0158]FIG. 40 is a schematic diagram of a feeding hopper for feedingbiomass.

[0159]FIG. 41 is a longitudinal cross-sectional view showing the tipportion of a screw feeder according to a conventional art.

[0160]FIG. 42 conceptionally depicts the state in which finelypulverized biomass is conveyed and discharged by means of the screwfeeder shown in FIG. 41.

[0161]FIG. 43 conceptionally depicts a biomass feeding unit according tothe thirtieth embodiment, wherein FIG. 43(A) is a side view of thefeeding unit; and FIG. 43(B) is a plan view of the feeding unit.

[0162]FIG. 44 is a longitudinal cross-sectional view showing an examplefluidization cone according to the thirtieth embodiment.

[0163]FIG. 45 is a longitudinal cross-sectional view showing anotherexample fluidization cone according to the thirtieth embodiment.

[0164]FIG. 46 depicts a biomass feeding unit according to thethirty-first embodiment, wherein FIG. 46(A) is a side view of thefeeding unit, and FIG. 46(B) is a plan view thereof.

[0165]FIG. 47 depicts an example tip portion of the screw feederaccording to the thirty-first embodiment, wherein FIG. 47(A) is alongitudinal cross-sectional view of the tip portion, and FIG. 47(B) isa right side view thereof.

[0166]FIG. 48 is a longitudinal cross-sectional view showing anotherexample tip portion of the screw feeder according to the thirty-firstembodiment.

[0167]FIG. 49 depicts a biomass feeding unit according to thethirty-second embodiment, wherein FIG. 49(a) is a side view of thefeeding unit and FIG. 49(b) is a plan view thereof.

[0168]FIG. 50 is an enlarged cross-sectional view showing structures ofa tip portion of the screw feeder of Example 1(A) and Example 2(B)according to the thirty-second embodiment.

BEST MODES FOR CARRYING OUT THE INVENTION

[0169] With reference to the accompanying drawings, the best modes forcarrying out the present invention will next be described in moredetail, which should not be construed as limiting the invention thereto.

[0170] [First Embodiment]

[0171] A first embodiment of the present invention will be describedwith reference to FIG. 1.

[0172]FIG. 1 shows a schematic view of a methanol synthesis systememploying a biomass gasification furnace according to the presentembodiment.

[0173] As shown in FIG. 1, a biomass gasification furnace 10 accordingto the present embodiment is an entrained-bed-type gasification furnacecomprising a biomass feeding means 13 for feeding biomass 11 to afurnace main body 12, and combustion-oxidizing agent feeding means 15which is located above the biomass feeding means 13 (i.e.; on thedownstream side of the furnace) and feeds a combustion-oxidizing agent(e.g.; O₂ or H₂O) 14 comprising oxygen or a mixture of oxygen and steamto the furnace main body 12.

[0174] The biomass 11 to be fed to the furnace main body 12 of thepresent invention is preferably a produced or waste biomass inpulverized, dried form.

[0175] As used herein, the word biomass refers to biological resources(such as agricultural products and by-products, lumber, and plants)which can be utilized as energy sources or industrial raw materials.Examples of such biological resources include sweet sorghum,nepiergrass, and spirulina.

[0176] In the present invention, the average particle size (D) of theaforementioned granular biomass 11 preferably falls within a range of0.05≦D≦5 mm. The reason is as follows. When the average particle size is0.05 mm or less, effect of pulverizing biomass becomes disadvantageouslypoor, whereas when the average particle size is in excess of 5 mm,biomass cannot be satisfactorily combusted to the innermost portion, andreaction is not accelerated, to thereby make high-efficiencygasification difficult.

[0177] In the present invention, the combustion-oxidizing agent 14 to befed to the biomass gasification furnace is preferably a mixture of airand steam or a mixture of oxygen and steam.

[0178] The aforementioned combustion-oxidizing agent 14 is added in suchan amount that the mol ratio of oxygen [O₂]/carbon [C] is controlled to0.1≦O₂/C, preferably 0.1≦O₂/C<1.0 (particularly preferably 0.2≦O₂/C<0.5)and the mol ratio of steam [H₂O]/carbon [C] is controlled to 1≦H₂O/C(particularly preferably 2≦H₂O/C≦6).

[0179] This is because when the aforementioned mol ratios fall withinthe above ranges, the supply of steam and oxygen enables satisfactorygasification through partial oxidation, to thereby increase the amountsof H₂ and CO in the produced gas with formation of soot and tar innegligible amounts.

[0180] The interior temperature of the biomass gasification furnace mainbody 12, which is one factor of gasification conditions, is preferablycontrolled to 700-1,200° C.

[0181] This is because when the interior temperature of the furnace islower than 700° C., thermal decomposition of biomass isdisadvantageously poor, whereas when the interior temperature is inexcess of 1,200° C., soot is undesirably generated through selfcombustion of biomass.

[0182] The internal pressure of the biomass gasification furnace mainbody 12 is preferably controlled to 1-30 atm.

[0183] The reason for this is, although a pressure of approximately 80atm is preferred for the direct synthesis of methanol (or dimethylether, etc.), such a high pressure calls for a pressure-resistantstructure of the gasification furnace, disadvantageously elevatingproduction costs.

[0184] An internal pressure of approximately 30 atm is preferred,because the superficial velocity can be lowered and the size of theequipment can be reduced.

[0185] The superficial velocity in the biomass gasification furnace mainbody 12, which is one factor of gasification conditions, is preferablycontrolled to 0.1-5 m/s.

[0186] This is because a superficial velocity equal to or lower than 0.1m/s prolongs the residence time in the furnace, resulting indisadvantageously excessive combustion, whereas a superficial velocityin excess of 5 m/s prevents complete combustion/thermal decomposition,to thereby fail to attain satisfactory gasification.

[0187] In order to attain optimal conveyance of pulverized biomass, theparticle size of the biomass is more preferably taken intoconsideration. When the average particle size of the biomass is 0.1-1mm, a superficial velocity of 0.4-1 m/s is particularly preferred, andwhen the average particle size is 1-5 mm, a superficial velocity of 1-5m/s is preferred.

[0188] The biomass gasification furnace according to the presentinvention provides clean gas without formation of soot or similarsubstances, because the furnace gasifies biomass efficiently throughpartial oxidization.

[0189] The aforementioned produced gas is purified by a gas purificationmeans, and thereafter, can directly serve as a fuel gas for a gasturbine.

[0190] Furthermore, by adjusting the compositional ratio of Hz to CO gascontained in the produced gas, the produced gas can be used also as agas for producing a substance such as methanol (or dimethyl ether).

[0191] Hereinbelow, a system in which the thus-obtained gas is employedfor methanol synthesis will be described.

[0192] <Methanol Synthesis System (1)>

[0193] As shown in FIG. 1, a methanol synthesis system 20 forsynthesizing methanol employing the above-described biomass gasificationfurnace comprises a dust collecting unit 22 for removing soot and dustfrom the produced gas generated in the furnace main body 12 of thebiomass gasification furnace 10; a purification unit 23 for purifyingthe dust-removed gas; a scrubber 24 for removing steam from the purifiedgas; a CO shift reaction unit 25 for regulating the compositional ratioof H₂ to CO gas in the thus-obtained gas; a booster unit 26 forelevating pressure of the gas; a methanol synthesis unit 27 forproducing methanol (CH₃OH) from H₂ and CO₂ contained in the pressurizedgas; and a gas-liquid separation unit 30 for separating discharge gas 28and methanol 29.

[0194] The biomass 11 which has been fed into the furnace main body 12of the gasification furnace 10 is partially combusted by use of thecombustion-oxidizing agent 14, and combusted under the aforementionedpredetermined conditions, to thereby improve efficiency of biomassgasification. The thus-produced gas 21 is subjected to dust removal inthe dust collecting unit 22, and then, transferred to the scrubber 24for removal of steam from the gas, where the gas is cooled, andsimultaneously, steam is removed. Subsequently, the H₂ content iselevated in the CO shift reaction unit, and the pressure of the gas iselevated by means of the booster 26 to a pressure suitable for methanolsynthesis. The pressurized gas is transferred to the methanol synthesisunit 27, where methanol is produced. Thereafter, discharge gas 28 andmethanol 29 are separated.

[0195] Since CH₄ remains in the above discharge gas 28, the gas can berecycled by being fed to the entrained-bed-type gasification furnace 10again.

[0196] The compositional ratio H₂/CO of the gas produced through theaforementioned gasification of biomass will be discussed hereinbelow.

[0197] The composition of biomass is represented by the C_(m)H₂O_(n)(m=1.0-1.5, n=0.7-1.1). However, for the purpose of convenience, thecomposition is represented simply by CH₂O and is employed in thefollowing description.

[0198] In general, methanol synthesis proceeds in accordance with thefollowing reaction scheme:

CO+2H₂→CH₃OH  (1)

[0199] In a conventional synthesis employing methane (CH₄) serving asnatural gas, the reaction proceeds as follows:

CH₄+H₂O→CO+3H₂  (2)

[0200] In a conventional synthesis employing fossil fuel (coal), thereaction proceeds as follows:

CH₂+H₂O→CO+2H₂  (3)

[0201] Generally, when biomass is just simply gasified, the reactionproceeds as follows:

CH₂O→CO+H₂  (4),

[0202] and the H₂/CO ratio never exceeds 2.

[0203] In order to solve this problem, in the present invention, acombustion-oxidizing agent 14 is introduced into a furnace, to therebycause partial combustion (CO+1/20₂→CO₂), and the produced heat is used.CO₂ is removed in a subsequent step, to thereby enhance the [H₂]/[CO]ratio.

[0204] Since the aforementioned reaction is endothermic, the reactionmust be carried out while heating. However, since heating of solidbiomass from the outside is difficult, gasification through partialcombustion is employed.

[0205] As used herein, the term “partial combustion” refers to a mode ofcombustion in which a portion of biomass serving as fuel is subjected tocombustion with a stoichiometrically insufficient amount of oxidizingagent (air or oxygen), so as to reserve a combustible gas of uncombustedfuel.

[0206] In order to promote partial oxidation reaction, thermaldecomposition, and gasification reaction, biomass is finely pulverizedso as to increase the reaction surface area. According to the presentinvention, this can be attained by adjusting the average particle size(D) of the granular biomass 11 to 0.05≦D≦5 mm.

[0207] Provided that biomass is represented by CH₂O, the basic reactionsof the biomass are as follows.

CH₂O→CO+H₂  (5) [endothermic reaction]

CH₂O+1/20₂→CO₂+H₂  (6) [exothermic reaction]

[0208] If the above reactions are achieved, a H₂/CO ratio of 2 or more,which is required for methanol synthesis, can be attained.

[0209] Heat of formation of the above-described reactions at 25° C. is:

[0210] for reaction (5); −26.4+27.7=+1.3 Kcal [endothermic reaction] and

[0211] for reaction (6); −94+27.7=−66.3 Kcal [exothermic reaction].Thus, the overall reaction is exothermic.

[0212] In the case in which CH₂O is completely combusted(CH₂O+O₂→CO₂+H₂O), the heat of formation is −124.3 (exothermic).

[0213] If the above-described reactions (5) and (6) were changed to acomplete combustion, the heat of formation would be as follows.

−124.3×2≡250 Kcal

[0214] Accordingly, in the overall reaction of (5) and (6):

−65.3/−250≡0.26,

[0215] which indicates a ratio of about 1/4 being justified to attain anideal combustion.

[0216] However, the above-described reaction generates less heat thancombustion reaction does. Thus, the temperature of the reaction fieldrises only to 450-500° C. (≡0.26×1,800-1,900° C.), resulting in aprolonged reaction time.

[0217] In order to maintain a combustion field at 800-1,000° C. whichallows the reaction to proceed, separate addition of high-temperaturevapor at approximately 400-500° C. is required.

[0218] To meet this requirement, a high-temperature steam (about400-500° C.) which has been obtained through heat exchange of the heatof high temperature gas produced in the gasification furnace main body12 is introduced separately.

[0219] The above-described gasification system utilizing the vapor andoxygen gas in combination is an ideal reaction system. However, anactual reaction system yields, other than CO and H₂, approximately 7-8%hydrocarbons such as CH₄, C₂H₄—C₂H₆, C₃H₆—, tar, and soot.

[0220] Hydrocarbons such as the aforementioned CH₄ can be converted toCO and H₂ through steam reforming at a temperature equal to or greaterthan 550° C. (suitably 900° C.±100° C.) in the presence of steam and anickel catalyst.

[0221] The H₂ obtained from the steam reforming can serve as a rawmaterial for methanol synthesis as described above.

[0222] In other words, by adding a steam reforming means to agasification system in which steam and oxygen are used in combination,CO and H₂ can be produced.

[0223] Thus, tar and soot, which are basically carbon-containingsubstances, can also undergo steam reforming if sufficient residencetime is provided.

[0224] Specifically, steam reforming of substances such as tar and sootis performed by means of a steam reforming means 31 comprising acatalyst (honeycomb radiation converter bearing a Ni catalyst thereon)placed between the dust collecting unit 22 and the purification unit 23,to thereby yield C and H₂.

[0225] When the biomass reaction proceeds as shown by reaction schemes(5) and (6), CO₂ is contained in the produced gas as a result of theemployment of internally generated heat.

[0226] CO₂ can also be used for methanol synthesis in the presence of ametallic catalyst such as Cu, Zn, or Cr, according to the followingreaction formula (7):

CO₂+3H₂→CH₃OH+H₂O  (7).

[0227] However, this formula contemplates only the balance among CO,CO₂, and H₂ in the produced gas, and unnecessary CO₂ merely expands thereaction system.

[0228] Thus, in order to improve the percent methanol recovery, excessCO₂ is preferably removed from the system in a contacting manner by useof a CO₂ removing unit provided for removing CO₂, such as an amine-basedwet CO₂ removing unit, in the final stage of the reaction system.

[0229] For this purpose, as shown in FIG. 1, a carbon dioxide removingunit 32 for removing CO₂ is interposed between the booster unit 26 andthe methanol synthesis unit 27, to thereby remove excess CO₂.

[0230] According to the present embodiment, not limiting the inventionthereto, the carbon dioxide removing unit 32 is interposed between thebooster unit 26 and the methanol synthesis unit 27, to thereby removeCO₂. Alternatively, the carbon dioxide removing unit 32 may be providedon the upstream side of the booster unit 26, to thereby remove CO₂ inadvance, and the resultant gas is pressurized by the booster unit 26.

[0231] Thus, through removal of excess CO₂, the gas serving as a rawmaterial for methanol production and to be introduced into the methanolsynthesis unit 27 has a composition of CO and 2H₂, to thereby proceedmethanol synthesis effectively, resulting in a yield of methanol ofabout 60% based on the biomass which has been supplied.

[0232] When a steam reforming means 31 is provided, the above-describedCO shift reaction unit 25 for generating H₂ can be omitted, because theamount of H₂ increases during the gasification step.

[0233] A portion of the thus-separated and thus-removed CO₂ can beutilized as a carrier gas of the biomass feeding means 13. Thus,introduction of unnecessary N₂ into the furnace can be prevented, when acarrier medium such as air is used.

[0234] [Second Embodiment]

[0235] <Methanol Synthesis System (2)>

[0236] A second methanol synthesis system according of the presentinvention will next be described.

[0237] Components having the same functions as those in the firstsynthesis system are denoted by the same reference numerals, andrepeated descriptions of such components are omitted.

[0238]FIG. 2 shows a schematic diagram of a methanol synthesis systemmaking use of biomass comprising a biomass gasification system employinga biomass gasification furnace according to the present embodiment.

[0239] As shown in FIG. 2, the biomass gasification system according tothe second embodiment comprises a biomass gasification furnace 10 forperforming gasification utilizing biomass (CH₂O) 11 and acombustion-oxidizing agent 14 fed to the furnace, to thereby form gasessuch as H₂ and CO; steam reforming means 31 for reforming, in thepresence of a nickel catalyst, hydrocarbon such as CH₄ contained inproduced gas 21 obtained through gasification in the biomassgasification furnace 10; a cooler 41 for cooling a gas reformed by meansof the steam reforming means 31; heat-exchanging means (not illustrated)which is installed in the cooler 41 and generates high-temperature steam43 through heat exchange with water 42 supplied from the outside; and agas purification unit 23 for purifying the cooled produced gas; a heatexchanger 44 for removing steam from the gas which has been purified bymeans of the purification unit 23; a booster unit 26 for elevating thepressure of the gas; a carbon dioxide removing unit 32 for removing CO₂contained in the pressurized gas; a regenerator 45 for heating thecarbon-dioxide-removed gas to a temperature suitable for methanolproduction; a methanol synthesis unit 27 for producing methanol (CH₃OH)from 2H₂ and CO contained in the gas; and a gas-liquid separation unit30 for separating the produced gas 46 obtained by means of the methanolsynthesis unit 27 into methanol 29 and discharge gas 28.

[0240] In the biomass gasification furnace 10 according to the secondembodiment, biomass 11 is introduced to a biomass feeding means 13 forfeeding biomass into a furnace main body 12, and steam 43 whosetemperature is elevated by use of the aforementioned heat-exchangingmeans is introduced into combustion-oxidizing agent feeding means 15, tothereby supply high-temperature steam to the biomass gasificationfurnace 10.

[0241] Preferably, the biomass 11 to be fed to the furnace main body 12according to the present invention is produced or waste biomass, and isdried by drying means 47, followed by pulverization to a predeterminedparticle size by a pulverization means 48.

[0242] In the methanol synthesis system according to the presentembodiment, the formed gas from which carbon dioxide gas has beenremoved by means of a carbon dioxide removing unit 32 is heated by aregenerator 45 for heating the carbon-dioxide-removed formed gas so asto raise the temperature of the CO₂-removed formed gas to a temperaturesuitable for methanol synthesis, to thereby enhance the efficiency ofmethanol synthesis.

[0243] In the above-described methanol synthesis system, biomass 11 isdried in advance in the biomass gasification furnace 10 for gasifyingbiomass serving as a raw material; then pulverized to a predeterminedparticle size; and fed into the furnace main body 12. In such anoperation, the biomass 11 is gasified through partial combustion at lowtemperature with O₂ in an amount ¼ the amount for the ideal combustion,while the heat attributed to CO₂ generated during the course of chemicalsynthesis is effectively utilized, to thereby elevate the interiortemperature of the gasification furnace. In addition, high-temperaturesteam 43 is supplied from the outside, to thereby to maintain theinterior temperature of the furnace at approximately 900° C., leading toproceed desirable gasification.

[0244] Although hydrocarbon such as CH₄ is generated in the formed gas21, the hydrocarbon is reformed into CO and H₂ by means of the steamreforming means 31 provided on the outlet side of the gasificationfurnace, to thereby attain a gas composition suitable for methanolsynthesis.

[0245] CO₂, which is unnecessary for synthesizing methanol, is removedto the outside by means of the carbon dioxide removing unit 32, tothereby attain a considerably ideal gas composition, wherein CO and H₂serving as essential components for methanol synthesis are contained andthe H₂/CO ratio is becomes 2<(H₂/CO). Moreover, the CO2-removed formedgas is heated by means of the regenerator 45 to a temperature suitablefor methanol synthesis, thereby enhancing the efficiency of methanolsynthesis.

[0246] Thus, by effective use of the biomass 11, a clean gas formethanol synthesis containing no generated soot or similar substances isobtained. The gas enhances methanol synthesis efficiency, andapproximate 60% the biomass 11 is converted to methanol fuel.

[0247] [Third Embodiment]

[0248] <Methanol Synthesis System (3)>

[0249] A third embodiment of the present invention will next bedescribed with reference to FIG. 3.

[0250]FIG. 3 is a schematic diagram of a methanol synthesis systemmaking use of a gas produced through gasification performed in a biomassgasification furnace according to the third embodiment.

[0251] Components having the same functions as those in theaforementioned methanol synthesis system are denoted by the samereference numerals, and repeated descriptions of such components areomitted.

[0252] In the biomass gasification system according to this embodiment,as shown in FIG. 3, unnecessary steam removed by means of theaforementioned heat exchanger 44 is used for heating and humidifyingoxygen serving as a combustion-oxidizing agent 14 to be fed into thefurnace main body 12 of the gasification furnace 10.

[0253] No particular limitation is imposed on the means for heating andhumidifying oxygen, and an indirect heat exchange method, which includesbubbling oxygen through heat-recovered water provided from an indirectheat exchanging means or a similar means, may be employed.

[0254] The thus-heated/humidified oxygen 49 is fed to the biomassgasification furnace 1Z via the combustion-oxidizing agent feeding means15, to thereby enhance efficiency of biomass gasification reaction.Thus, latent heat of low-temperature steam at about 50° C. which hasbeen obtained by means of the heat exchanger 44 can be effectivelyrecovered.

[0255] [Fourth Embodiment]

[0256] <Methanol Synthesis System (4)>

[0257] A fourth embodiment of the present invention will be describedwith reference to FIG. 4.

[0258]FIG. 4 is a schematic diagram of a methanol synthesis systememploying a biomass gasification furnace according to the presentembodiment.

[0259] Components having the same functions as those in theaforementioned methanol synthesis system are denoted by the samereference numerals, and repeated descriptions of such components areomitted.

[0260] As shown in FIG. 4, the biomass gasification system according tothis embodiment comprises a biomass gasification furnace 10 forgasifying fed biomass 11; a gas purification unit 23 for purifying a gas21 produced through gasification in the biomass gasification furnace 10and cooled by means of a cooler 41; a heat exchanger 44 for removingsteam from the purified gas; a CO shift reaction unit 25 for adjustingthe compositional ratio of H₂ to CO gas of the cooled gas; a boosterunit 26 for elevating the pressure of the gas; a carbon dioxide removingunit 32 for removing CO₂ contained in the gas to the outside; aregenerator 45 for heating the carbon-dioxide-removed, pressurized gasto a temperature for methanol production; a methanol synthesis unit 27for producing methanol (CH₃OH) from H₂ and CO contained in the gas; anda gas-liquid separation unit 30 for separating the synthesized gas 46obtained by means of the methanol synthesis unit 27 into methanol 29 anddischarge gas 28.

[0261] In the aforementioned embodiment, CH₄ contained in the gasproduced through gasification is reformed into H₂ and CO by employmentof a steam reforming means 31. However, in this embodiment, H₂ requiredfor the methanol synthesis is produced by the CO shift reaction unit 25,instead of the steam reforming means 31. Although CO₂ is generated inthe aforementioned CO shift reaction unit 25, excess CO₂ is removed fromthe reaction system to the outside by means of the aforementioned carbondioxide removing unit 32.

[0262] As described in connection to the aforementioned embodiment, CO₂removed by the carbon dioxide removing unit 32 may be used as a gas forcarrying biomass 11. In addition, oxygen serving as acombustion-oxidizing agent 14 may also be heated and humidified by meansof the high-temperature steam 43 provided from the cooler 41.

[0263] [Fifth Embodiment]

[0264] <Methanol Synthesis System (5)>

[0265] A fifth embodiment of the present invention will be describedwith reference to FIG. 5.

[0266]FIG. 5 is a schematic diagram of a methanol synthesis systemmaking use of a gas produced through gasification performed in a biomassgasification furnace according to the fifth embodiment.

[0267] As shown in FIG. 5, the methanol synthesis system according tothe present embodiment comprises a biomass gasification furnace 10 forgasifying biomass 11 fed into the furnace; a steam reforming means 31for reforming, in the presence of a nickel catalyst, hydrocarbons suchas CH₄ contained in the gas 21 produced through gasification in thebiomass gasification furnace 10; a cooler 41 for cooling the gasreformed by the steam reforming means 31; a gas purification unit 23 forpurifying the gas cooled by the cooler 41; a heat exchanger 44 forremoving steam contained in the purified gas; a CO shift reaction unit25 for regulating the compositional ratio of H₂ to CO gas contained inthe cooled gas; a booster unit 26 for pressurizing the resultant gas; acarbon dioxide removing unit 32 for removing to the outside CO₂contained in the gas; a regenerator 45 for heating thepressurized/carbon-dioxide-removed gas to a temperature suitable formethanol production; a methanol synthesis unit 27 for producing methanol(CH₂OH) from H₂ and CO contained in the gas; and a gas-liquid separationunit 30 for separating the gas 46 synthesized by the methanol synthesisunit 27 into discharge gas 28 and methanol 29.

[0268] In the aforementioned first and other embodiments, CH₄ containedin the gas produced through gasification is reformed into H₂ and CO byemployment of the steam reforming means 31. However, in this embodiment,a larger amount of Hz, required for methanol synthesis, is obtainedthrough employment of the CO shift reaction unit 25 in combination withthe steam reforming means. Although the CO shift reaction unit 25generates CO₂, excess CO₂ is separated by the aforementioned carbondioxide removing unit 32.

[0269] As described in connection with the aforementioned embodiment,CO₂ removed by the carbon dioxide removing unit 32 may be used as acarrier gas for the biomass 11. In addition, oxygen to be fed as thecombustion-oxidizing agent 14 may also be heated and humidified by theheat exchanger 44.

[0270] [Sixth Embodiment]

[0271] <Methanol Synthesis System (6)>

[0272] A sixth embodiment of the present invention will next bedescribed with reference to FIG. 6.

[0273]FIG. 6 is a schematic diagram of a methanol synthesis systemmaking use of a gas produced through gasification performed in a biomassgasification furnace according to the sixth embodiment.

[0274] As shown in FIG. 6, the methanol synthesis system according tothe sixth embodiment comprises a biomass gasification furnace 10 forgasifying biomass 11 fed into the furnace; a gas purification unit 23for purifying gas 21 produced through gasification in the biomassgasification furnace 10 and cooled by a cooler 41; a heat exchanger 44for removing steam contained in the purified gas; a CO shift reactionunit 25 for regulating the compositional ratio of H₂ to CO gas containedin the cooled gas; a booster unit 26 for pressurizing the gas; a carbondioxide removing unit 32 for removing CO₂ contained in the gas to theoutside the system; a regenerator 45 for heating the pressurized,carbon-dioxide-removed gas to a temperature suitable for methanolproduction; a methanol synthesis unit 27 for producing methanol (CH₃OH)from H₂ and CO contained in the gas; and a gas-liquid separation unit 30for separating the synthesized gas into discharge gas 28 and methanol29. In this gasification system, residual CH₄ contained in the dischargegas 28 separated by the gas-liquid separation unit 30 is recirculatedinto the biomass gasification furnace 10.

[0275] Thus, heat generated through combustion of the residual CH₄ inthe discharge gas 28 can be utilized for partial oxidation, and thegenerated CO₂ is removed by means of the carbon dioxide removing unit32. Since the composition of the gas for methanol synthesis remainsconstant by removing generated CO₂by means of the carbon dioxideremoving unit 32, methanol synthesis in the methanol synthesis unit 27can be performed steadily.

[0276] The aforementioned discharge gas 28 yielded through gas-liquidseparation may be effectively employed as a carrier gas for carrying thegranular biomass 11 to the biomass gasification furnace 10, therebyfeeding the biomass into the furnace.

[0277] The aforementioned discharge gas 28 can be used for driving a gasengine so as to effectively serve in the system as a power source forvarious equipment, such as a pulverizer for biomass, and an oxygenproduction unit for producing oxygen.

[0278] [Seventh Embodiment]

[0279] <Methanol Synthesis System (7)>

[0280] A seventh embodiment of the present invention will next bedescribed with reference to FIG. 7.

[0281]FIG. 7 is a schematic diagram of a methanol synthesis systemmaking use of a gas produced through gasification performed in a biomassgasification furnace according to the seventh embodiment.

[0282] As shown in FIG. 7, the methanol synthesis system according tothe seventh embodiment comprises a biomass gasification furnace 10 forgasifying biomass 11 fed into the furnace; a gas purification unit 23for purifying the gas 21 produced through gasification in the biomassgasification furnace 10 and cooled by a cooler 41; a heat exchanger 44for removing steam contained in the purified gas; a CO shift reactionunit 25 for regulating the compositional ratio of H₂ to CO gas containedin the cooled gas; a booster unit 26 for pressurizing the gas; a carbondioxide removing unit 32 for removing CO₂ contained in the gas to theoutside of the system; a regenerator 45 for heating the pressurized gasto a temperature suitable for methanol production; a methanol synthesisunit 27 for producing methanol (CH₃OH) from H₂ and CO contained in thegas; and a gas-liquid separation unit 30 for separating synthesized gasinto discharge gas 28 and methanol 29. In this system, a steam turbine53, serving as a power sources for units such as a circulation blower 52and the booster unit, is driven by use of steam 51 produced byrecovering heat generated from methanol synthesis performed in themethanol synthesis unit 27.

[0283] The reaction carried out in the aforementioned methanol synthesisunit 27 is exothermic, and the thus-generated heat is used, attainingeffective heat utilization in the system.

[0284] In addition, a portion of gas, contained in the methanolsynthesis unit 27, is recycled to a site on the upstream side of thecarbon dioxide removing unit 32 by means of the circulation blower 52,so as to enhance the efficiency of the synthesis. A portion of therecycled gas 54 can be employed in the drying means 47 as a gas fordrying biomass 11.

[0285] [Eighth Embodiment]

[0286] <Methanol Synthesis System (8)>

[0287] An eighth embodiment of the present invention will next bedescribed with reference to FIG. 8.

[0288]FIG. 8 is a schematic diagram of a methanol synthesis systemmaking use of a gas produced through gasification performed in a biomassgasification furnace according to the eighth embodiment.

[0289] As shown in FIG. 8, the biomass gasification system according tothe seventh embodiment is mounted on a mounting base 55; or the entiretyof the system mounted on the mounting base 55 is mounted on a travelingcarriage 56; or the entirety of the system is mounted directly on thetraveling carriage 56, so as to make the system movable.

[0290] As shown in FIG. 8, the entire system is mounted on the mountingbase 55. The entirety mounting base 55 may be covered with a cover 57 soas to protect the apparatus therein. In order to move or transfer thesystem by suspending the same by means of a crane or similar means,lifting lugs 58 may be attached to the four corners of the mounting base55, further enhancing operability.

[0291] Furthermore, by mounting the entire system on the travelingcarriage 56, a movable system can be attained. The traveling carriage 56may be equipped with wheels for towing by a tractor, or the travelingcarriage 56 is equipped with driving means, to thereby make the system aself-moving biomass gasification system.

[0292] Alternatively, the system mounted on the mounting base 55 may bemounted on the traveling carriage 56 so as to transfer the system.

[0293] According to the present embodiment, the dimensions of thebiomass gasification system can be considerably reduced as compared witha conventional technique. Therefore, the system can be suspended bymeans of a crane or a similar means; can be moved or towed by conveyingmeans; or can move itself to an arbitrary site, attaining excellenttransportability.

[0294] Thus, the system is capable of being transferred to the sitewhere biomass is produced or waste is collected, to thereby gasify thebiomass and produce methanol at the site.

[0295] Such transportability according to the eighth embodiment may besimilarly imparted to the systems according to the aforementionedembodiments as well as the systems described hereinafter.

[0296] [Ninth Embodiment]

[0297] <Methanol Synthesis System (9)>

[0298] A ninth embodiment of the present invention will be describedwith reference to FIG. 9.

[0299]FIG. 9 is a schematic diagram of a methanol synthesis systemmaking use of a gas produced through gasification performed in a biomassgasification furnace according to the ninth embodiment.

[0300] As shown in FIG. 9, the methanol synthesis system according tothe ninth embodiment comprises a biomass gasification furnace 10 forgasifying biomass 11 fed thereto; a gas purification unit 23 forpurifying gas 21 produced through gasification in the gasificationfurnace 10 and cooled by means of a cooler 41; a heat exchanger 44 forremoving steam from the purified gas; a CO shift reaction unit 25 forregulating the compositional ratio of H₂ to CO gas contained in thecooled gas; a booster unit 26 for elevating the pressure of the gas; aregenerator 45 for elevating the temperature of the pressurized gas to atemperature suitable for methanol synthesis; a methanol synthesis unit27 for producing methanol (CH₃OH) from H₂ and CO contained in the gas;and a gas-liquid separation unit 30 for separating, from the synthesisgas, a discharge gas 28 and methanol 29. In this methanol synthesissystem, the heat of reaction (approximately 300° C.) generated from thecatalytic reaction in the methanol synthesis unit 27 is exchanged bywater 71 discharged from the heat exchanger 44 in a first heat exchanger72 provided inside the methanol synthesis unit 27.

[0301] Subsequently, the steam 73 having heat-exchanged is introducedinto the cooler 41 for cooling the gas 21 produced from the gasificationfurnace 10, so as to recover the heat from high-temperature produced gas(e.g.; approximately 900° C.) through heat exchange in a second heatexchanger 74 provided inside the cooler 41. The thus-obtainedhigh-temperature (400-600° C.) steam 75 is fed to the biomassgasification furnace 10.

[0302] The high-temperature steam 75 obtained in the system can beutilized as a component of the combustion-oxidizing agent 14, to therebyenhance efficiency of the methanol synthesis system employing biomass.

[0303] [Tenth Embodiment]

[0304] <Methanol Synthesis System (10)>

[0305] A tenth embodiment will next be described with reference to FIG.10.

[0306]FIG. 10 is a schematic diagram of a methanol synthesis systemmaking use of a gas produced through gasification performed in a biomassgasification furnace according to the tenth embodiment.

[0307] Components having the same functions as those in theaforementioned methanol synthesis system are denoted by the samereference numerals, and repeated descriptions of such components areomitted.

[0308] As shown in FIG. 10, in the methanol synthesis system accordingto the tenth embodiment, the heat exchanger 44 for cooling the gaspurified by the gas purification unit 26 and for removing moisture inthe gas, comprises a water sprinkling means 44A for sprinkling water 76;and an alkaline water sprinkling means 44B for sprinkling alkalinesolution 77 (e.g., NaOH). Heat recovery is carried out in a mannersimilar to that employed in the ninth embodiment, employing dischargewater 71 resulting from sprinkling of water by the water sprinklingmeans 44A, to thereby obtain high-temperature steam 75 and feed thesteam into the gasification furnace 10.

[0309] According to the present embodiment, the purified gas is firstintroduced into the water sprinkling means 44A, where the gas is cooledand moisture contained in the gas is recovered by sprinkling water 76.Subsequently, the thus-obtained gas is introduced into the alkalinewater sprinkling means 44B for sprinkling an alkaline solution 77 (e.g.;NaOH), where acidic gases (e.g.; ammonia gas, hydrogen chloride, and asulfur component (H₂S)) are removed from the gas by sprinkling thealkaline water.

[0310] Similar to the case of the ninth embodiment, in a first heatexchanger 72, discharge water 71 drained from the water sprinkling means44A is subjected to heat-exchange with heat (approximately 300° C.)generated by catalytic reaction carried out in the methanol synthesisunit 27. Subsequently, the gas 21 produced from the gasification furnace10 is fed to a cooling means 41, to thereby recover heat of the producedhigh temperature gas (e.g.; at approximately 900° C.) in a second heatexchanger 74. The resultant high-temperature steam 75 is supplied to thebiomass gasification furnace 10.

[0311] In addition to the effect obtained from the ninth embodiment, thepresent embodiment employs a two-stage scrubber including the watersprinkling means 44A and the alkaline water sprinkling means 44B. Thus,cooling and moisture removal are effected by sprinkled water 76 at afirst-stage, and at a second-stage, an acidic gas is removed bysprinkled alkaline water 77, to thereby prevent deterioration of unitsand piping on the downstream side caused by corrosion etc.

[0312] [Eleventh Embodiment]

[0313] <Methanol Synthesis System (11)>

[0314] A eleventh embodiment of the present invention will be describedwith reference to FIG. 11.

[0315]FIG. 11 is a schematic diagram of a methanol synthesis systemmaking use of a gas produced through gasification performed in a biomassgasification furnace according to the eleventh embodiment.

[0316] Components having the same functions as those in theaforementioned methanol synthesis system are denoted by the samereference numerals, and repeated descriptions of such components areomitted.

[0317] The methanol synthesis system according to the present embodimentincludes a first adsorption column or guard column 78 provided betweenthe aforementioned booster unit 26 and regenerator 45 in the methanolsynthesis system; and a second adsorption column or guard column 79provided between the aforementioned regenerator 45 and methanolsynthesis unit 27.

[0318] The aforementioned adsorption columns are filled with a substancehaving adsorption capability, such as silica gel or activated carbon.The guard columns are filled with a catalyst which is also employed inthe methanol synthesis unit 27. They are “disposable” columns which areto be disposed or regenerated after use for a predetermined period oftime.

[0319] These adsorption columns or guard columns are effective toprevent poisoning of a catalyst in the methanol synthesis system.Therefore, the methanol synthesis can be performed steadily for a longperiod of time.

[0320] In the present embodiment, two-stage protection is attained byuse of the first adsorption column or guard column 78 and the secondadsorption column or guard column 79. However, the present invention isnot limited thereto. For example, only the first adsorption column orguard column 78 may be employed.

[0321] [Twelfth Embodiment]

[0322] <Methanol Synthesis System (12)>

[0323] A twelfth embodiment of the present invention will be describedwith reference to FIG. 12.

[0324]FIG. 12 is a schematic diagram of a methanol synthesis systemmaking use of a gas produced through gasification performed in a biomassgasification furnace according to the twelfth embodiment.

[0325] Components having the same functions as those in theaforementioned methanol synthesis system are denoted by the samereference numerals, and repeated descriptions of such components areomitted.

[0326] The methanol synthesis system according to the twelfth embodimenteffectively utilizes H₂ contained in discharge gas 28 which has beenseparated through gas/liquid separation of the gas 46 produced in amethanol synthesis unit 27.

[0327] As shown in FIG. 12, the produced gas 46 synthesized by theaforementioned methanol synthesis unit 27 is separated into methanol 29and discharge gas 28 by means of a gas/liquid separation unit 30.Generally, the discharge gas 28 is fed back to a site on the upstreamside of the regenerator 45 without any additional treatment. However, inthis embodiment, a hydrogen (H₂) separation unit 80 for isolating onlyH₂ from the relevant discharge gas 28 is employed, to thereby elevatethe H₂ content in the discharge gas 28 to be recycled.

[0328] The hydrogen separation unit 80 may employ a known hydrogenseparation technique such as H₂ separation on the basis of a pressureswing technique or membrane separation.

[0329] According to the present embodiment, H₂ is exclusively isolatedby the hydrogen separation unit 80, and the isolated H₂ is recycled to asite on the upstream side of the regenerator 45. Therefore, residual H₂can be used effectively, leading to improved efficiency of hydrogenutilization for methanol synthesis.

[0330] [Thirteenth Embodiment]

[0331] <Methanol Synthesis System (13)>

[0332] A thirteenth embodiment of the present invention will next bedescribed with reference to FIG. 13.

[0333]FIG. 13 is a schematic diagram of a methanol synthesis systemmaking use of a gas produced through gasification performed in a biomassgasification furnace according to the thirteenth embodiment.

[0334] Components having the same functions as those in theaforementioned methanol synthesis system are denoted by the samereference numerals, and repeated descriptions of such components areomitted.

[0335] The methanol synthesis system according to the thirteenthembodiment employs a methanol synthesis unit having two separatesynthesis systems so as to continuously synthesize methanol.

[0336]FIG. 14 shows an enlarged view of a methanol synthesis unitaccording to the thirteenth embodiment shown in FIGS. 13 and 14, themethanol synthesis unit 81 according to the present embodiment includestwo separate synthesis systems; i.e., a first synthesis column 82 and asecond synthesis column 83.

[0337] The first synthesis column 82 comprises valves 84 a and 84 bprovided at both ends of the column. In the first synthesis column 82, acatalyst layer 82-1 serving as a first stage through a catalyst layer82-5 serving as a final stage (five stages in this embodiment) areprovided. Similarly, the second synthesis column 83 comprises valves 85a and 85 b provided at both ends of the column. In the second synthesiscolumn 83, a catalyst layer 83-1 serving as a first stage through acatalyst layer 83-5 serving as a final stage (five stages in thisembodiment) are provided.

[0338] According to the thirteenth embodiment, as shown in FIG. 14, thefirst synthesis column 82 and the second synthesis column 83 areemployed alternately during methanol synthesis. For example, during useof the first synthesis column 82, the valves 85 a and 85 b of the secondsynthesis column 83 are closed. Among catalyst layers of the secondsynthesis column 83, the degraded first-stage catalyst layer 83-1provided in the vicinity of the gas inlet is removed, and thesecondstage catalyst layer 83-2 is shifted to the position of the firststage. The remaining catalyst layers are shifted successively, and a newcatalyst layer is placed as the final stage, to thereby sequentiallysubstitute a degraded portion by a new catalyst layer.

[0339] Through the aforementioned substitution, the second-stagecatalyst layer serves as a first-stage catalyst layer, to therebymaintain desirable catalyst activity, attaining excellent methanolsynthesis.

[0340] Through the employment of the thirteenth embodiment, ease ofmaintenance of the methanol synthesis unit is improved.

[0341] In the thirteenth embodiment, although a guard column 78 isprovided on the upstream side of the regenerator 45, the guard column 78is not essential. However, provision of the guard column 78 preventspoisoning of the catalyst and decrease in catalyst activity.

[0342] Alternatively, guard columns may be employed as the first-stagecatalyst layers 82-1 and 83-1, and may be disposed of after use for apredetermined period of time.

[0343] The present embodiment employs two series of catalytic synthesiscolumns. However, the present invention is not limited thereto, and aplurality of series of synthesis columns may be employed for theenhancement of synthesis efficiency.

[0344] [Fourteenth Embodiment]

[0345]FIG. 15 shows a schematic view of a biomass gasification furnaceaccording to the fourteenth embodiment.

[0346] In a biomass gasification furnace 10 according to the presentembodiment, a combustion-oxidizing agent 14 which contains oxygen or amixture of oxygen and steam is fed to a furnace main body 12 through amulti-stage-feeding method.

[0347] According to the present embodiment, as shown in FIG. 15, feedingmeans 15A to 15D are provided for feeding the combustion-oxidizing agent14 via a plurality of points which are provided along the perpendicularaxis of the furnace main body 12. The feeding means 15A to 15D areprovided upward in a sequential manner at predetermined intervals, sothat the combustion-oxidizing agent 14 for promoting gasification is fedsequentially downstream with respect to the gas flow.

[0348] According to the present embodiment, biomass 11 is fed by abiomass feeding means 13 so that the biomass is supplied from the lowersection of the furnace main body 12, and a plurality of feeding ports(two ports in the case of this embodiment) of the combustion-oxidizingagent feeding means 15A are provided at predetermined points onconcentric circles centering the feeding port 13 a of the feeding means13.

[0349] Therefore, since the combustion-oxidizing agent 14 is fed in asequential manner from a plurality of stages, gasification efficiency isimproved.

[0350] Employment of a gasification furnace according to the presentembodiment serving as the gasification furnace for the aforementionedmethanol synthesis system will improve the efficiency of the methanolsynthesis.

[0351] [Fifteenth Embodiment]

[0352]FIG. 16 is a schematic diagram of a biomass gasification furnaceaccording to the fifteenth embodiment. As shown in FIG. 16, the biomassgasification furnace 10 according to the fifteenth embodiment acomprises biomass feeding means 13 for feeding biomass 11 into thefurnace main body 12; a combustion-oxidizing agent feeding means 15,provided at a site on the upstream side of the biomass feeding means 13(on the downstream side of the furnace), for feeding acombustion-oxidizing agent 14 comprising oxygen or a mixture of oxygenand steam into the furnace main body 12; and a plurality ofnickel-catalyst-on-ceramic foam plates 61 provided within the upperportion of the furnace such that the plates alternately extend inopposite directions.

[0353] The ceramic foam plates 61 capture tar and soot contained in thegas generated through gasification of biomass 11 and decompose capturedtar substances into CO and H₂ by the action of nickel catalysts, tothereby provide a gas having a composition suitable for methanolsynthesis.

[0354] Since the aforementioned plates of ceramic foam 61 also serve asradiation converters, a uniform gasification temperature throughout theinterior of the gasification furnace main body 12 can be attained,resulting in enhancement of gasification reaction efficiency in thegasification furnace main body 12.

[0355] In the present embodiment, high-temperature steam 43 isintroduced from the outside through the bottom section of the furnacemain body 12.

[0356] [Sixteenth Embodiment]

[0357]FIG. 17 is a schematic diagram of a biomass gasification furnaceaccording to a sixteenth embodiment.

[0358] As shown in FIG. 17, the biomass gasification furnace 10according to the present embodiment comprises a plurality ofNi-catalyst-on-ceramic foam plates 61 provided at a site on thedownstream side of the bent portion of the upper portion 12a of thefurnace main body 12 such that the plates alternately extend in oppositedirections.

[0359] The ceramic foam plates 61 capture tar and soot contained in thegas generated through gasification of biomass 11 and decompose capturedtar substances into CO and H₂ by the action of nickel catalysts, tothereby provide a gas having a composition suitable for methanolsynthesis.

[0360] Ash 62 deposited on the ceramic foam 61 can be discharged to theoutside through unillustrated means such as steam spraying.

[0361] [Seventeenth Embodiment]

[0362]FIG. 18 shows a schematic diagram of a biomass gasificationfurnace according to the seventeenth embodiment. As shown in FIG. 18,the biomass gasification furnace 10 according to the seventeenthembodiment produces a gas 21 through gasification/combustion of biomass11 and a combustion-oxidizing agent 14, such as oxygen, at hightemperature. The biomass gasification furnace 10 includes, at a topsection 12b of a gasification furnace main body 12 made of a refractorymaterial, a biomass feeding means 13 for feeding biomass 11 which hasbeen pulverized to a predetermined grain size into the furnace; and acombustion-oxidizing agent feeding means 15 for feeding acombustion-oxidizing agent 14, such as a mixture of oxygen or air andsteam, into the furnace main body 12.

[0363] The lower section of the furnace main body 12 includes an ashreceiving section 92 for receiving combustion residue 91 containingsubstances that remain uncombusted after gasification. The wall definingthe ash receiving section 92 makes a cooling jacket 93 having adownwardly reduced diameter.

[0364] A gas discharge tube 94 is provided in a lower section of theside wall of the furnace main body 12. The gas discharge tube 94discharges gas 21 produced by biomass gasification.

[0365] In the present embodiment, the biomass 11 is fed downward fromthe top section 12 b of the biomass gasification furnace 10. Therefore,even when biomass contains large amounts of low-melting-pointsubstances, unlike the case in which biomass is blown upward, depositionof uncombusted components onto the inner wall surface of the furnace canbe prevented, thereby realizing continuous biomass gasification.

[0366] Particularly, when biomass containing a larger amount of analkaline component, such as an Na salt, a K salt, and a P salt, is usedas starting material, the ash melting point lowers to as low as 600° C.However, feeding the biomass 11 from the top section 12 b of the furnaceprevents deposition and formation of ash.

[0367] According to the present invention, biomass of any compositionother than biomass having a specific high melting point can be gasified.The invention provides a gasification furnace highly suited for generalpurposes, not for specific biomass of high melting point.

[0368] Since solid ash is deposited to the inner surface of the ashreceiving section 92 through cooling by the cooling jacket 93,deposition between the ash and the inner surface is weak. Therefore, theash can be forcedly removed through blowing of steam by use of, forexample, soot removing means.

[0369] [Eighteenth Embodiment]

[0370]FIG. 19 shows a schematic diagram of a biomass gasificationfurnace according to the present embodiment. Components identical withthose in the gasification furnace of the above-described embodiments arerepresented by the same reference numerals, and repeated descriptions ofsuch components are omitted.

[0371] As shown in FIG. 19, the biomass gasification furnace 10according to the eighteenth embodiment includes a hollow cylindricalgas-ash introducing means 95 having a downwardly reduced diameter, whichmeans is provided above and in the vicinity of a gas discharge tube 94provided in the side wall of the lower portion of the gasificationfurnace main body 12, the upper end of the means 95 being joined to theinner surface of the main body, and an ash separation chamber 96 beingprovided below the gas-ash introducing means 95.

[0372] According to the present embodiment, since the gas-ashintroducing means 95 and the ash separation chamber 96 are provided, theflow rates of the gas and ash which are introduced into the ashseparation chamber 96 from the ash introducing means 95 are reduced inthe chamber 96. Therefore, the ash and the gas are easily separated fromeach other, and transfer of the ash to the gas discharge tube 94 isprevented.

[0373] In this embodiment, a cooling jacket 93 is provided so as toextend from the central portion to the lower portion of the gasificationfurnace main body, and soot removing means (desludger) 97 for injectingsteam toward the inner surface of the furnace is provided, therebyfacilitating removal of solid matter deposited to the inner surface.

[0374] The soot removing means 97 of this embodiment has two injectionopenings 97 a facing each other in an offset manner. However, thepresent invention is not limited thereto, and, if necessary, theposition of each injection opening may be changed, and the number of theinjection openings may be increased.

[0375] As shown in FIG. 20, a water bath section 98 may be provided atthe lower section of the gasification furnace so as to recover theseparated ash in a wet state.

[0376] [Nineteenth Embodiment]

[0377]FIG. 21 shows a schematic diagram of a biomass gasificationfurnace according to the nineteenth embodiment. Components identicalwith those in the gasification furnace of the above-describedembodiments are represented by the same reference numerals, and repeateddescriptions of such components are omitted.

[0378] The biomass gasification furnace 10 according to the presentembodiment includes a water bath section 98 provided at the lowerportion of a gasification furnace main body 12; and a hollow cylindricalgas introducing means 95 having a downwardly reduced diameter, the tipend portion 95 a of the means 95 being dipped in the water bath section98.

[0379] In this embodiment, a water-cooling tube 99 is provided in such amanner that the tube 99 extends from the central portion to the lowerportion of the gasification furnace main body 12 so as to cool the sidewall of the main body 12.

[0380] According to the nineteenth embodiment, since the produced gas ispassed once through the water bath section 98, water contained in thegas is removed.

[0381] Since the gas is introduced into the water bath section, a traceamount of ash contained in the gas is actively cooled and solidified.

[0382] Particularly, the nineteenth embodiment is suitable forgasification of biomass which produces ash of low melting point.

[0383] [Twentieth Embodiment]

[0384]FIG. 22 shows a schematic diagram of a biomass gasificationfurnace according to the twentieth embodiment. Components identical withthose in the gasification furnace of the above-described embodiments arerepresented by the same reference numerals, and repeated descriptions ofsuch components are omitted.

[0385] As shown in FIG. 22, the biomass gasification furnace 10according to the present embodiment includes a gas discharge tube 101for discharging a produced gas 21 and provided at the center of the topsection 12 b of a gasification furnace main body 12, the gas dischargetube 101 vertically extending such that a lower portion of the gasdischarge tube projects into the interior of the gasification furnacefor a predetermined length, and a lower end opening 101 a of the gasdischarge tube 101 faces the interior of the gasification furnace.

[0386] The lower portion of the gasification furnace main body 12 has ahollow cylindrical shape having a downwardly reduced diameter, and awater bath section 98 is provided at the lower side of the main body 12,to thereby trap melted ash.

[0387] According to the present embodiment, biomass 11 is downwardly fedto the gasification furnace. However, since the gas 21 produced throughgasification is discharged upward through the gas discharge tube 101, agasification region increases, to thereby enhance gasificationefficiency.

[0388] Since the entirety of the lower portion of the gasificationfurnace main body has a downwardly reduced diameter, the produced gas 21is concentrated to the central portion of the main body, to therebyefficiently introduce the gas 21 into the discharge tube 101.

[0389] Since the lower portion of the gasification furnace main body hasa downwardly reduced diameter, melted ash readily falls, to therebyincrease the trapping ratio of the melted ash in the water bath section98.

[0390] [Twenty-First Embodiment]

[0391]FIG. 23 shows a schematic diagram of a biomass gasificationfurnace according to the present embodiment. Components identical withthose in the gasification furnace of the above-described embodiments arerepresented by the same reference numerals, and repeated descriptions ofsuch components are omitted.

[0392] As shown in FIG. 23, the biomass gasification furnace 10according to the present embodiment has a structure such that thediameter D, of the aforementioned gasification furnace main body 12 inthe portion below the central portion is slightly smaller than thediameter D₂ of the main body 12 in the portion above the centralportion, and a partition 102 is vertically provided in such a mannerthat one end of the partition 102 is joined to the inner wall surface ofthe smaller-diameter portion of the main body. By providing thepartition 102 inside the furnace main body, a path 103 for introducing aproduced gas and ash and a gas discharge path 104 are formed, so as toallow the produced gas and ash to pass through the path, and the flow ofthe produced gas 21 is turned upward at the end 102 a of the partition102, thereby separating the ash from the produced gas and allowing thegas to pass through the gas discharge path 104 for discharge through aproduced gas discharge tube 94.

[0393] In the twenty-first embodiment, heat exchangers 105A, 105B, and105C are provided in the gas-ash introducing path 103 and the gasdischarge path 104, to thereby subject latent heat of the gas to heatexchange.

[0394] According to the twenty-first embodiment, separation of theproduced gas 21 can be carried out efficiently, and steam, etc. areeffectively utilized through recovery of the latent heat of the gas.

[0395] [Twenty-Second Embodiment]

[0396] In the above-described embodiments, biomass is employed as a rawmaterial for gasification. In this embodiment, one example ofgasification by use of a fossil fuel, such as coal, will be described.

[0397] In a twenty-second embodiment, biomass is combusted incombination with a fossil fuel. Examples of the fossil fuel include coaland heavy oil.

[0398]FIG. 24 shows a schematic diagram of a biomass gasificationfurnace according to the twenty-second embodiment. As shown in FIG. 24,the biomass gasification furnace 10 according to the twenty-secondembodiment is an entrained-bed-type gasification furnace, comprising abiomass feeding means 13 for feeding biomass 11 to a furnace main body12; a combustion-oxidizing agent feeding means 15 for feeding acombustion-oxidizing agent 14 containing oxygen or a mixture of oxygenand steam to the furnace main body 12, the means 15 being provided below(i.e.; on the downstream side of the furnace) the biomass feeding means;a coal feeding means 17 for feeding coal 16 to the furnace, the means 17facing the combustion-oxidizing agent feeding means 15; and a steamfeeding means 19 for feeding steam 18, the means 19 being provided at acentral position between the coal feeding means 17 and the biomassfeeding means 13.

[0399] In the twenty-second embodiment, in order to provide a combustionaid portion at the lower portion of the furnace main body 12, coal 16serving as fossil fuel is fed to the furnace, and a high-temperatureportion is formed through combustion of coal 16 serving as fossil fuel,without permitting combustion of biomass 11. The biomass 11 is fed tothe thus-formed high temperature portion, to thereby efficiently carryout thermal decomposition and gasification of the biomass 11. In thisembodiment, the combustion-oxidizing agent is employed also as a fuelfor providing the high-temperature portion.

[0400] Heretofore, when reaction proceeds slowly in the case in which,for example, the calorific value of biomass is low, fossil fuel issupplied together with the biomass. According to the present invention,since fossil fuel and biomass are supplied separately through differentpositions, a high-temperature portion is provided at a combustion aidportion without self-combustion of biomass, and the biomass is gasifiedat the high-temperature portion. Therefore, gasification of the biomasscan be carried out at high efficiency.

[0401] As a result, a gas suitable for methanol synthesis can beproduced at high efficiency and low cost; conversion of carbon can beenhanced; problems caused by, for example, deposition of tar and a likesubstance can be eliminated, and the feed amount of oxygen or air can bereduced. In addition, a gas containing a large amount of hydrogen can beproduced.

[0402] In the case in which coal 16 is employed as fossil fuel, the coalmay be pulverized to form coal micropowder, and conveyed in the form ofa gas mixture containing steam and air, or steam and oxygen.

[0403] In addition, when a heavy oil or an oil typically employed forcombustion is employed to promote combustion, these oils may be sprayedinto the furnace in the form of a gas mixture containing a spray medium,such as steam and air, or steam and oxygen.

[0404] [Twenty-Third Embodiment]

[0405] In a twenty-third embodiment, biomass is fed to a coalgasification furnace, so as to enhance the efficiency of the productionof a gas for methanol synthesis.

[0406]FIG. 25 schematically shows a conventional two-stageentrained-bed-type gasification furnace comprising a combustor and areductor. As shown in FIG. 25, the two-stage entrained-bed-typegasification furnace comprises a combustion furnace 03 comprisingtherein a combustor 01, for carrying out combustion, and a reductor 02for carrying out gasification reaction, the reductor 02 being providedabove the combustor 01; a coal micropowder feeding means 05 for feeding,into the combustor 01, coal micropowder 04 obtained by pulverizing coal;an air supplying means 07 for supplying air, oxygen-enriched air, oroxygen 06 for combustion; and a coal micropowder feeding means 08 forfeeding, into the reductor 02, coal micropowder 04. Construction of agasification furnace is not limited to the embodiment shown in FIG. 25,wherein the regions of the combustor and the reductor are not clearlydefined by a narrowed portion.

[0407] The coal micropowder 04 fed from the coal micropowder feedingmeans 05 is subjected to high-temperature—high-load combustion in thepresence of air, oxygen-enriched air, or oxygen 06 for combustion. Thethus-generated high-temperature combustion gas is fed to the reductor02. The coal micropowder 04 is sprayed into the reductor 02 from theseparately provided coal micropowder feeding means 08, and is subjectedto dry-distillation by use of the high-temperature combustion gasgenerated in the combustor 01, thereby causing gasification.

[0408] A gas 09 formed through gasification is purified, andsubsequently, the resultant gas is transported to a gas turbine to beutilized for generating electricity.

[0409] However, the gas 09 formed through gasification of coalpredominantly contains CO has a low calorific value and a poor hydrogencontent. Thus, the gas 09 is not suitable to serve as a raw material formethanol synthesis. Therefore, development of a method for gasificationthrough employment of a coal gasification furnace that produces a gashaving a useful composition for methanol synthesis has been desired.

[0410] Accordingly, the coal gasification furnace of the presentembodiment is drawn to a two-stage entrained-bed-type gasificationfurnace, comprising, as shown in FIG. 26, a combustion furnace 113equipped therein with a combustor 111 for carrying out combustion and areductor 112 for carrying out gasification, the reductor 112 beingprovided above the combustor 111; a coal micropowder feeding means 115for feeding, to the combustor 111, coal micropowder 114 obtained throughpulverization of coal; means for feeding air, oxygen-enriched air, oroxygen (hereinafter referred to as “air, etc. feeding means”) 117 forfeeding air or oxygen-enriched air or oxygen (hereinafter referred to as“air, etc.”) 116 for combustion; a coal micropowder feeding means 118for feeding coal micropowder 114 to the reductor 112; and a biomassfeeding means 13 for feeding pulverized biomass 11 to the reductor 112.

[0411] In the above apparatus, the coal micropowder 114 fed through thecoal micropowder feeding means 115 is subjected tohigh-temperature—high-load combustion in the presence of air, etc. 116for aiding combustion. The resultant high-temperature combustion gas isfed to the reductor 112. The coal micropowder 114 fed from theseparately provided coal micropowder feeding means 118 and the biomass11 fed by the biomass feeding means 13 are injected into the reductor112, and are subjected to dry-distillation under the high-temperaturecombustion gas generated in the combustor 111, to thereby gasify thebiomass, yielding a produced gas 21.

[0412] As shown in FIG. 27, in the case in which coal micropowder 114and biomass 11 are fed separately, methods for feeding biomass include:(1) a method in which the coal micropowder 114 and the biomass 11 arefed through positions which are oppositely facing each other (as shownin FIG. 27(A)); or (2) an offset method in which the biomass 11 is fedthrough the position provided slightly above the position through whichthe coal micropowder 114 is fed (as shown in FIG. 27(B)). The coalmicropowder or the biomass may be fed through a plurality of positions.

[0413] In addition to biomass feeding methods shown in FIG. 27, coalmicropowder 114 and biomass 11 may be fed through a single feeding tube132, as shown in FIG. 28.

[0414] As shown in FIG. 29, the feeding tube 132 may have a dualstructure in which tubes are provided concentrically, such that biomass11 is fed through an inner tube 133 and the coal micropowder 114 is fedthrough an outer tube 134, to thereby inject them into the reductor 112.

[0415] As shown in FIG. 30, a biomass feeding portion 135 may further beprovided above the reductor 112 in the combustion furnace 113 shown inFIG. 26, so as to feed biomass 11 to the biomass feeding portion 135.This structure can prevent combustion of the biomass 11 in the reductor112, which may otherwise occur in a combustion furnace shown in FIG. 26.Therefore, gasification efficiency is improved.

[0416] In the present embodiment, as shown in FIG. 26, a steam reformingmeans 31 (for example, Ni-catalyst-carrying ceramic foam (ahoneycomb-type radiation exchanger) 124) may be provided, according toneeds, in the vicinity of the outlet of the combustion furnace, suchthat the ratio of H₂ to CO contained in a gas obtained throughgasification in the combustion furnace 113 satisfies 2<[H₂]/[CO].

[0417] Thus, the temperature in the reductor 112 of the combustionfurnace 113, which is one factor of gasification conditions, iscontrolled to 700-1,200° C. (preferably about 800-1,000° C.).

[0418] This is because when the temperature in the furnace is lower than700° C., combustion proceeds unsatisfactorily, whereas when thetemperature is in excess of 1,200° C., soot is disadvantageouslygenerated due to combustion of the biomass itself.

[0419] The superficial velocity in the combustion furnace 113, which isone factor of gasification conditions, is not particularly limited, andis preferably controlled to 0.1-5 m/s similar to that employed in thebiomass gasification furnace described in the first embodiment.

[0420] In the above biomass gasification furnace 113, the gas 14produced through gasification of biomass 11 may contain, other than theaforementioned H₂, CO, and CO₂, hydrocarbons such as CH₄, C₂H₄—C₂H₆,C₃H₆—, tar, and soot, depending on the gasification conditions.

[0421] Hydrocarbons such as the aforementioned CH₄ can be converted toCO and H₂ by means of the steam reforming means 31 at a temperatureequal to or greater than 550° C. (suitably 900° C.±100° C.) in thepresence of steam and a nickel catalyst. The H₂ obtained from the steamreforming means 31 can serve as a raw material for methanol synthesis asdescribed above.

[0422] In other words, by adding the steam reforming means 31 forsteam-reforming a gas 21 produced from the supplied biomass to a coalgasification system, CO and H₂ can be produced.

[0423] Thus, tar and soot, which are basically carbon-containingsubstances, can also undergo steam reforming if sufficient residencetime is provided.

[0424] According to the aforementioned coal gasification furnace, sincefed coal and biomass 11 are gasified, the gas produced throughgasification has a compositional ratio of H₂/CO greater than 2.Therefore, gasification and reforming are carried out efficiently, and agas having an excellent composition for methanol synthesis can beobtained.

[0425] The produced gas is purified in the gas purification unit, andthe compositional proportions of gas components in the gas areregulated, to thereby provide a raw material for the synthesis ofvarious fuels (e.g., methanol and ethanol).

[0426] A system, according to the present embodiment, for synthesizingmethanol for use as fuel will next be described with reference to FIG.31. As shown in FIG. 31, the methanol synthesis system according to thepresent embodiment includes the aforementioned purification unit 23 forremoving dust, etc. from the gas 21 produced in the combustion furnace113 and cooled by means of a cooler 41, to thereby purify the gas; aheat exchanger 44 for removing steam from the purified gas; a boosterunit 26 for increasing the pressure of the gas; a carbon dioxideremoving unit 32 for removing CO₂ from the pressure-increased gas; aregenerator 45 for heating the carbon-dioxide-removed gas to thetemperature for methanol production; a methanol synthesis unit 27 forproducing methanol (CH₃OH) from 2H₂ and CO contained in the gas; and agas-liquid separation unit 30 for separating the gas 46 produced in themethanol synthesis unit 27 into methanol 29 and a discharge gas 28.

[0427] The above methanol synthesis system includes the carbon dioxideremoving unit 32 for removing unnecessary CO₂ from the gas 21 producedthrough gasification, the gas containing CO, CO₂, and H₂. Therefore,excess CO₂ is removed from the system in a contacting manner at a finalstage of the system by use of the carbon dioxide removing unit forremoving CO₂, for example, an amine-wet-type carbon dioxide removingunit, to thereby increase the recovery percentage of methanol.

[0428] Thus, as shown in FIG. 31, the carbon dioxide removing unit 32for removing CO₂ is provided between the booster unit 26 and themethanol synthesis unit 27, to thereby remove excess CO₂. Alternatively,the carbon dioxide removing unit 32 may be provided on the upstream sideof the booster unit 26, to thereby increase the pressure of the gas fromwhich CO₂ has been removed in advance.

[0429] Therefore, since excess CO₂ is removed from the methanol rawmaterial gas fed to the methanol synthesis unit 27, the gas has acomposition of CO and 2H₂, to thereby efficiently effect methanolsynthesis, i.e.; to attain high-efficiency synthesis.

[0430] CO₂ removed from the gas in the carbon dioxide removing unit 32may be recycled as a carrier gas for the biomass.

[0431] According to the present invention, gasification of coalmicropowder and biomass can be effectively performed. Thus, the gascomposition of the produced gas becomes suitable for methanol synthesis.

[0432] In addition, as shown in FIG. 31, if necessary, the steamreforming means 31 may be provided at the outlet of the gasificationfurnace, to thereby reform, in the vicinity of the outlet of thegasification furnace, hydrocarbons contained in the produced gas 21 intoCO and H₂ and attain a gas composition suitable for methanol synthesis.

[0433] CO₂, which is unnecessary for methanol synthesis, is removed bythe carbon dioxide removing unit 32 to the outside, and the resultantgas contains CO and 2H₂, which are required for methanol synthesis. Theratio of H₂/CO in the gas becomes greater than 2, to thereby provide anremarkably ideal gas for methanol synthesis.

[0434] [Twenty-Fourth Embodiment]

[0435] A methanol synthesis system, according to the twenty-fourthembodiment of the present invention, employing a coal gasificationfurnace will be described with reference to FIG. 32.

[0436] As shown in FIG. 32, the methanol synthesis system making use ofbiomass according to the present embodiment includes a combustionfurnace 113 for gasifying fed biomass 11; a gas purification unit 23 forpurifying the produced gas 21 obtained through gasification in thecombustion furnace 113 and is cooled by means of a cooler 41; a heatexchanger 44 for removing steam from the purified gas; a CO shiftreaction unit 25 for regulating the compositional ratio of H₂ to CO gasin the cooled gas; a booster unit 26 for increasing the pressure of thegas; a carbon dioxide removing unit 32 for removing CO₂ from the gas tothe outside of the system; a regenerator 45 for heating thepressure-increased and CO₂-removed gas to the temperature for methanolproduction; a methanol synthesis unit 27 for producing methanol (CH₃OH)from H₂ and CO contained in the gas; and a gas-liquid separation unit 30for separating a gas 46 synthesized in the methanol synthesis unit 27into a discharge gas 28 and methanol 29.

[0437] In the aforementioned system shown in FIG. 31 according to thetwenty-third embodiment, CH₄ contained in the gas produced throughgasification is reformed into H₂ and CO through the steam reformingmeans 31. In contrast, in the system according to the presentembodiment, H₂, which is essential for methanol synthesis, is obtainedby use of the CO shift reaction unit 25. Although CO₂ is generated inthe CO shift reaction unit 25, excess CO₂ is removed through separationof CO₂ by use of the carbon dioxide removing unit 32.

[0438] As described in connection with the first embodiment, CO₂ removedby the carbon dioxide removing unit 32 may be employed as a carrier gasfor biomass 11.

[0439] [Twenty-Fifth Embodiment]

[0440]FIG. 33 shows a schematic diagram of a biomass gasification systememploying a biomass gasification furnace according to the twenty-fifthembodiment.

[0441] As shown in FIG. 33, the methanol synthesis system, according tothe present embodiment, making use of biomass includes a gasificationcombustion furnace 113 for gasifying fed biomass 11; a steam reformingmeans 31 for reforming hydrocarbons such as CH₄ contained in a gas 14produced through gasification in the combustion furnace 113, in thepresence of a nickel catalyst; a cooler 41 for cooling the gas which isreformed through the steam reforming means 31; a gas purification unit23 for purifying the gas which has been cooled in the cooler 41; a heatexchanger 44 for removing steam from the purified gas; a CO shiftreaction unit 25 for regulating the compositional ratio of H₂ to CO gasin the cooled gas; a booster unit 26 for increasing the pressure of thegas; a carbon dioxide removing unit 33 for removing CO₂ from the gas tothe outside of the system; a regenerator 45 for heating thepressure-increased and CO2-removed gas to the temperature for methanolproduction; a methanol synthesis unit 27 for producing methanol (CH₃OH)29 from H₂ and CO contained in the gas; and a gas-liquid separation unit30 for separating a gas 46 synthesized in the methanol synthesis unit 27into a discharge gas 28 and methanol 29.

[0442] In the above-described twenty-third embodiment, CH₄ contained inthe gas produced through gasification is reformed into H₂ and CO throughreformation by means of the steam reforming means 31. In the presentembodiment, H₂, which is necessary for methanol synthesis, is obtainedin a large amount by use of the CO shift reaction unit 25. Although CO₂is generated in the CO shift reaction unit 25, excess CO₂ is removedthrough separation of CO₂ by use of the carbon dioxide removing unit 32.

[0443] [Twenty-Sixth Embodiment]

[0444] In the biomass gasification furnaces according to the first andthe fourteenth through the twenty-first embodiments, the to-be-gasifiedbiomass serving as a raw material is efficiently gasified by employmentof a combination of combustion and gasification of biomass fed to afurnace. The present invention alternatively provides anotherconfiguration of biomass gasification in which combustion andgasification are carried out efficiently in a separate field.

[0445] In such a biomass gasification furnace, biomass (e.g., in theform of plants) is subjected to partial oxygen gasification.Specifically, exothermic reaction (combustion reaction) of biomassrepresented by the below-described formula (A) and endothermic reaction(thermal decomposition reaction) of biomass represented by thebelow-described formula (B) are carried out in combination in onechamber, to thereby gasify the biomass. In relation to gas producedthrough the combination reaction, the proportions of gas components inthe synthesis gas; i.e., CO/H₂/CO₂ (by mol), are preferably0.9-1.0/1.8-2.2/about 1.

CH₂O+1/20₂→CO₂+H₂  formula (A)

CH₂O→CO+H₂  formula (B)

[0446] A typical form of biomass (C_(m)H₂O_(n)) is represented by CH₂O.

[0447] In the aforementioned biomass gasification furnace, exothermicreaction of biomass and endothermic reaction of biomass, which arecounteractive to each other, are carried out in combination in onechamber. Therefore, the following problems arise.

[0448] In order to attain the aforementioned combination reaction and toproduce a desired gas form, exothermic reaction and endothermicreaction, which are counteractive to each other, must be carried out andcontrolled promptly. Therefore, from the viewpoints of heat generation(combustion) and heat absorption (thermal decomposition), biomass mustbe formed into fine particles (particle size: tens of microns). However,when fibrous biomass is formed into fine particles, the type ofpulverizing machine is limited, and the pulverization power unit must belarge. In accordance with the size of biomass fine particles, the systemfor powder handling, including storage, discharge, transportation, andsupply of the powder of biomass, becomes complicated, and may encounterdifficulty.

[0449] Since exothermic reaction of biomass and endothermic reaction ofbiomass, which are counteractive to each other, must be carried outsimultaneously and in combination, control of the reactions becomescomplex.

[0450] When the aforementioned biomass gasification furnace is employedin a methanol production unit, control of the reactions becomessimilarly complicated.

[0451] An object of the invention is to provide a biomass gasificationfurnace which is easily controlled and which eliminates the necessity ofpulverizing biomass into fine particles.

[0452] Another object of the invention is to provide a methanolproduction unit which is easily controlled, which unit employs thebiomass gasification furnace which is easily controlled, and whicheliminates the necessity of pulverizing biomass into fine particles.

[0453]FIG. 34 schematically depicts a twenty-sixth embodiment of thebiomass gasification furnace according to the invention. In FIG. 34,reference numerals 201 and 202 represent a combustion chamber and agasification chamber, respectively, the chambers being providedseparately. A combustion space 203 is provided in the combustion chamber201. A gasification space 204 is provided in the gasification chamber202.

[0454] A reaction tube 205 formed from a heat-resistant material isprovided in the gasification chamber 202. The gasification space 204 isprovided in the reaction tube 205. A combustion gas feeding passage 206is provided between the inside wall surface of the gasification chamber202 and the outside wall surface of the reaction tube 205. The reactiontube 205 includes a large number of perforations 208 for uniformlyfeeding a combustion gas 207 (represented by a solid arrow in FIG. 34)from the combustion gas feeding passage 206 to the reaction tube 205.The gasification chamber 202 and the reaction tube 205 have a dual-tubestructure.

[0455] A combustion gas feeding line 209 for feeding the combustion gas207 from the combustion space 203 to the gasification space 204 isprovided between the combustion space 203 in the combustion chamber 201and a portion of the combustion gas feeding passage 206 located at alower portion of the gasification chamber 202.

[0456] A feeding unit 211 and a feeding line 212 for feeding biomass 210for combustion (represented by a thick solid arrow in FIG. 34) areconnected to the upper portion of the combustion chamber 201. Adischarge valve 224 and a discharge line 225 for discharging ash 223(represented by a two-dot arrow in FIG. 34) are connected to the bottomof the combustion chamber 201. In addition, a feeding control valve 214and a feeding line 215 for feeding an oxidizing agent 213 (representedby a dashed arrow in FIG. 34) such as oxygen or air are connected to thelower portion of the combustion chamber 201.

[0457] In the combustion chamber 201, a heat exchanger 216 serving asheat recovery means is provided on the side close to the combustion gasfeeding line 209. The heat exchanger 216 has the ability to absorb heatby use of water and to remove dust. A flow control valve 218 and afeeding line 219 for feeding water 217 (represented by a one-dot arrowin FIG. 34) are connected to the heat exchanger 216. A pressure controlvalve 221 and a feeding line 222 for feeding steam 220 (represented by aone-dot arrow in FIG. 34) are connected between the heat exchanger 216and the upper portion of the combustion chamber 201. The steam feedingline 222 is connected to the upper portion of the combustion chamber 201at a location between the feeding line 212 for feeding biomass forcombustion and the heat exchanger 216. The steam feeding line 222 may bebranched, and the branched line may be connected to the lower portion ofthe combustion chamber 201 via a pressure control valve (notillustrated).

[0458] A feeding unit 227 and a feeding line 228 for feeding biomass 226for gasification (represented by a thick solid arrow in FIG. 34) areconnected through the gasification chamber 202 to the top of thereaction tube 205. A discharge line 230 for discharging a synthesizedgas 229 (represented by an outlined arrow or a double-solid arrow inFIG. 34) is connected to the upper portion of the reaction tube 205. Inaddition, a discharge valve 232 and a discharge line 233 for dischargingash 231 (represented by a two-dotted arrow in FIG. 34) are connectedthrough the gasification chamber 202 to the bottom of the reaction tube205. Further, a control valve 234 and a discharge line 235 fordischarging the combustion gas 207 are connected to a portion of thecombustion gas feeding passage 206 located at the upper portion of thegasification chamber 202.

[0459] Heat exchangers (not illustrated), serving as heat recoverymeans, may be provided on the discharge line 230 for the synthesis gas229 and on the discharge line 235 for the combustion gas 207, to therebyfeed the water 217 to the heat exchanger 216 in the combustion chamber201 through the heat exchangers on the synthesis gas discharge line 230and on the combustion gas discharge line 235. Means for recovering thenon-reacted biomass 226 for gasification; for example, a cyclone (notillustrated), may be provided between the reaction tube 205 and thedischarge line 230 for the synthesis gas 229. An opening (notillustrated) for feeding the biomass 210 for combustion may be providedon the combustion chamber 201, and an opening and closing cap (notillustrated) may be provided on the opening such that the opening can beopened and closed.

[0460] Operation of the biomass gasification furnace of the twenty-sixthembodiment having the aforementioned structure will next be described.

[0461] The biomass 210 for combustion and the oxidizing agent 213 arefed to the combustion space 203 in the combustion chamber 201. Thebiomass 210 is combusted in the combustion space 203, in which theratio, the oxidizing agent 213/the biomass 210, is 0.5-0.7. Combustionof the biomass 210 is carried out through ignition by use of an ignitionburner (not illustrated).

[0462] Through combustion of the biomass 210, the combustion gas 207 isgenerated in the combustion space 203. The steam 220 is fed to thecombustion chamber 201. Through feeding of the steam 220, generation ofcarbon or soot, which may be generated through combustion of the biomass210 in the combustion space 203, can be suppressed. Steam is suitablyemployed particularly in the gasification furnace according to thetwenty-sixth embodiment, in which the combustion gas 207 in thecombustion space 203 is fed, as a heat source, to the gasification space204.

[0463] The combustion gas 207 containing the steam 220 has a temperatureof 800-1,100° C., which is suitable for gasification (thermaldecomposition) of the below-described biomass 226 for gasification, andhas a calorific value necessary for the gasification; i.e., a calorificvalue two to three times the product of the amount of the biomass 226and the reaction heat absorption value. The temperature and thecalorific value of the combustion gas 207 containing the steam 220 arecontrolled by regulation of (the oxidizing agent 213)/(the biomass 210)ratio, regulation of the amount of water 217 fed to the heat exchanger216, or regulation of the amount of the steam 220 fed to the combustionchamber 201.

[0464] In the combustion space 203, by the dust removal effect of theheat exchanger 216, biomass and ash dispersed in the combustion space203 are removed, to thereby prevent the flow of such dust into thegasification chamber 202 provided on the downstream side of thecombustion chamber. Such a heat exchanger is suitably employedparticularly in the gasification furnace according to the twenty-sixthembodiment, in which the combustion gas 207 produced in the combustionspace 203 is fed, as a heat source, to the gasification space 204.

[0465] The residual ash 223 of the biomass 210 combusted in thecombustion space 203 is precipitated and accumulated at the bottom ofthe combustion chamber 201. The precipitated and accumulated ash 223 isperiodically discharged through the discharge valve 224 and thedischarge line 225 to the outside of the combustion chamber 201.

[0466] The combustion gas 207 containing the steam 220 is fed throughthe combustion gas feeding line 209 to a portion of the combustion gasfeeding passage 206 located at the lower portion of the gasificationchamber 202. At the inlet of the gasification chamber 202, preferably,the combustion gas 207 containing the steam 220 has a temperature of600-1,000° C. and has a gas form containing no non-reacted carbon and asmall amount of H₂O, in which the mol ratio of CO₂/H₂ is 0.9-1.1(preferably 1). When air is used as the oxidizing agent 213, thecombustion gas 207 containing the steam 220 naturally contains inert N₂gas.

[0467] In accordance with the form of the below-described biomass 226for gasification, the amount and the pressure of the combustion gas 207containing the steam 220 at the inlet of the gasification chamber 202are regulated by the control valve 234 of the discharge line 235 for thecombustion gas 207.

[0468] The biomass 226 for gasification is fed to the gasification space204 in the reaction tube 205 of the gasification chamber 202. In thegasification space 204, gasification (i.e., thermal decomposition,hereinafter referred to as “gasification”) of the biomass 226 proceedswhile the biomass 226 is caused to flow by the combustion gas 207containing the steam 220. The pressure of the gasification space 204 inthe reaction tube 205 is generally maintained at ambient pressure to 10ata.

[0469] In the reaction tube 205, the flow velocity (superficialvelocity) of the biomass 226 for gasification is preferably about 0.1m/s or less. The flow velocity of the biomass 226 is set at the abovevalue, in order to prevent dispersion of the biomass 226 and the ashremaining after gasification to the outside of the reaction tube 205,and to secure a sufficient reaction time (about 30-60 seconds), overwhich the biomass 226 stays within the reaction tube 205 forgasification.

[0470] The reaction tube 205 includes a large number of perforations208, so that the combustion gas 207 is uniformly fed to the interior ofthe reaction tube 205. Owing to this structure of the tube 205, thebiomass 226 for gasification is uniformly gasified in the reaction tube205. Therefore, the efficiency of gasification of the biomass 226 isenhanced.

[0471] In the reaction tube 205, the biomass 226 for gasification isgasified, to thereby produce the synthesis gas 229 predominantlycontaining CO, H₂, CO₂, and H₂O (and N₂ when combustion is effected inthe presence of air). In the biomass gasification furnace according tothe twenty-sixth embodiment, the combustion gas 207 (CO₂, H₂) producedin the combustion chamber 201 which is provided separately from thegasification chamber is fed to the reaction tube 205, and the combustiongas is mixed with the gas (CO, H₂) produced through gasification of thebiomass 226, to thereby obtain the synthesis gas 229 (CO₂, CO, 2H₂). Inthe biomass gasification furnace according to the twenty-sixthembodiment, the calorific value necessary for gasification of thebiomass 226, which is generally an endothermic reaction, is obtainedfrom the combustion gas 207 produced in the combustion chamber 201 whichis provided separately from the gasification chamber.

[0472] In the synthesis gas 229, the mol proportions of the gascomponents CO, H₂, and CO₂ are preferably 0.9-1.0/1.8-2.2/about 1.Particularly, from the viewpoint that methanol is synthesized from thesynthesis gas 229, the mol ratio of CO/H₂ must be 1/2. In the biomassgasification furnace according to the twenty-sixth embodiment, the molproportions of the gas components in the synthesis gas 229 are regulatedby control of gasification (basically, control of the form of thebiomass 226 serving as a raw material) in the reaction tube 205 of thegasification chamber 202, and by control of combustion in the combustionchamber 201 serving as a heat feeding source.

[0473] Combustion in the combustion chamber 201 is controlled by, forexample, regulation of the amount of the biomass 210 for combustion,regulation of the ratio of the oxidizing agent 213, regulation of theamount of the steam 220 for temperature control, and regulation of theheat exchanger 216 for calorie control.

[0474] H-65)

[0475] The synthesis gas 229 produced in the reaction tube 205 is fedthrough the discharge line 230 to a unit provided downstream; forexample, a methanol synthesis unit (not illustrated). Excess gas of thecombustion gas 207 serving as a heat source of gasification isdischarged through the control valve 234 and the discharge line 235 tothe outside of the gasification chamber 202. When heat exchangersserving as heat recovery means are provided on the discharge line 230and the discharge line 235, discharged heat can be recovered. The excessgas (the combustion gas 207) may be utilized as a heat source forincreasing the reaction temperature of a catalyst (i.e. a heat sourcefor heating a catalyst) in a methanol synthesis unit. Alternatively, theexcess gas (the combustion gas 207) may be recovered through a recoveryline (not illustrated) to the combustion space 203 in the combustionchamber 201.

[0476] Reaction residual ash 231 resulting from the reaction of theto-be-gasified biomass 226 in the gasification space 204 of the reactiontube 205 is discharged intermittently, to the outside of thegasification chamber 202, from the lower portion of the reaction tube205 through the discharge line 233 and the discharge valve 232.

[0477] The biomass gasification furnace according to the twenty-sixthembodiment includes the combustion chamber 201 and the gasificationchamber 202, which are provided separately, in which the combustionspace 203 for combusting the to-be-combusted biomass 210 and thegasification space 204 for gasifying the to-be-gasified biomass 226 areprovided, respectively.

[0478] As a result, in the biomass gasification furnace according to thetwenty-sixth embodiment, exothermic reaction of biomass and endothermicreaction of biomass, which are counteractive to each other, are carriedout independently in the combustion space 203 and the gasification space204, respectively. Thus, biomass is not necessarily pulverized (to sometens of microns) in order to cause the counteractive exothermic andendothermic reactions promptly. Particularly, the particle size ofto-be-gasified biomass 226 in the order of a few millimeter issufficient. Furthermore, the biomass gasification furnace according tothe twenty-sixth embodiment is easily controlled, since thecounteractive reactions, exothermic and endothermic reactions ofbiomass, can be controlled independently.

[0479] In the biomass gasification furnace according to the twenty-sixthembodiment, the melting point of the ash 231 of the biomass 226 forgasification varies within a range of 750-1,500° C., in accordance withthe type of the biomass 226. When the melting point of the ash 231 issufficiently high (e.g.; 900° C. or higher) with respect to thegasification temperature (700-900° C.), there hardly arises the problemthat the ash 231 is melted in the reaction tube 205, and thus flow ofthe biomass 226 is impeded and discharge of the ash 231 becomesdifficult. However, when the melting point of the ash 231 is 900° C. orlower, the aforementioned problems in relation to melting of the ash 231may arise, because of the relationship between the melting point of theash and the gasification temperature.

[0480] In the biomass gasification furnace according to the twenty-sixthembodiment, such a problem can be prevented by lowering the gasificationtemperature, while sacrificing the gasification reaction to some extent.In the biomass gasification furnace according to the twenty-sixthembodiment, since exothermic reaction of biomass and endothermicreaction of biomass are controlled individually, such a problem can besolved.

[0481] [Twenty-Seventh Embodiment]

[0482]FIG. 35 schematically depicts the biomass gasification furnaceaccording to Embodiment 27 of the present invention. In FIG. 35,reference numerals identical with those in FIG. 34 represent the samecomponents.

[0483] A grate 237 having a large number of perforations 236 is providedat the lower portion of a combustion chamber 201. An ignition burner 238is also provided at the lower portion of the combustion chamber 201. Arecovery line 239 for a combustion gas 207 is provided at the upperportion of the combustion chamber 201.

[0484] A line (not illustrated) for feeding steam to suppress generationof carbon or soot may be provided in a combustion space 203 of thecombustion chamber 201. A heat recovery means (not illustrated) and/or adust removing means (not illustrated) may be provided in the combustionspace 203 of the combustion chamber 201. In addition, an opening (notillustrated) for feeding biomass 210 for combustion may be provided onthe combustion chamber 201, and an opening and closing cap (notillustrated) may be provided on the opening such that the opening can beopened or closed.

[0485] A reaction tube 240 is provided in a gasification chamber 202.The reaction tube 240 is formed of a metallic tube, for example, aquartz tube or a Pyrex glass tube.

[0486] A receiving plate 241 is provided at the lower portion of thegasification chamber 202. The lower portion of the reaction tube 240 isheld by the receiving plate 241. A large number of perforations 242 areprovided in the receiving plate 241, so as to communicate with thereaction tube 240.

[0487] Heat exchangers 243 and 244, serving as heat recovery means, areprovided on a discharge line 230 for a synthesis gas 229 and on adischarge line 235 for the combustion gas 207, respectively. A feedingline 246 for feeding steam 245 (represented by a one-dot arrow in FIG.35) is connected between the heat exchangers 243 and 244 and the lowerportion of the gasification chamber 202. The steam 245 is heated steamhaving a temperature of 400-500° C. Cooling water is heated in the heatexchanger 243, to thereby form steam, and the resultant steam is heatedin the heat exchanger 244 to obtain heated steam.

[0488] Means for recovering non-reacted biomass 226 for gasification;for example, a cyclone (not illustrated), may be provided between thereaction tube 240 and the discharge line 230 for the synthesis gas 229.

[0489] Operation of the biomass gasification furnace according to thetwenty-seventh embodiment having the aforementioned structure will nextbe described.

[0490] In the combustion space 203 of the combustion chamber 201,granular or chip-like biomass 210 for combustion is completely combustedthrough ignition by the ignition burner 238 and by use of an oxidizingagent 213 fed through the perforations 236 in the grate 237 provided atthe lower portion of the combustion chamber 201. While maintaining apredetermined temperature (about 800-1,100° C.) and calorific value, thecompletely combusted clean combustion gas 207 is fed to a gas feedingpassage 206 of the gasification chamber 202. The temperature and thecalorific value of the combustion gas 207 are controlled by theaforementioned regulation.

[0491] The heat of the combustion gas 207 fed to the gas feeding passage206 is supplied from the outside of the reaction tube 240 to the insidethereof. The biomass 226 for gasification is fed to the reaction tube240 from the upper portion, and the steam 245 containing no oxygen (thesteam 245 is a gasification agent and heated steam having a temperatureof 400-500° C.) is fed upward to the reaction tube 240 from the lowerportion. As a result, while the biomass 226 is caused to flow by thesteam 245, the biomass 226 is gasified by the radiation heat of thereaction tube 240, to thereby produce the synthesis gas 229.

[0492] In general, the aforementioned reaction in which biomass(C_(m)H₂O_(n)) serves as a raw material and steam (H₂O) serves as agasification agent includes elementary reactions represented by thefollowing formulas (C), (D), and (E).

CO+H₂O→CO₂+H₂  formula (C)

C+H₂O→CO+H₂  formula (D)

C+2H₂O→CO₂+2H₂  formula (E)

[0493] In order to synthesize methanol from the synthesis gas 229, themol ratio of CO/H₂ is preferably 1/2. Therefore, in order to smoothlycarry out the above-described reactions represented by formulas (C),(D), and (E), some regulation means are necessary. As one suchregulation means, the inner temperature of the reaction tube 240 isregulated. The temperature is regulated at 700-1,000° C., preferably700-900° C., more preferably 700-800° C. The inner temperature of thereaction tube 240 is controlled by regulation of the amount and thetemperature of the combustion gas 207 and by regulation of the amountand temperature of the steam 245.

[0494] The synthesis gas 229 which is produced in the reaction tube 240and is accompanied by some dispersion granules is fed through thedischarge line 230 and the heat exchanger 243 to a unit provideddownstream; for example, a methanol synthesis unit (not illustrated).Excess gas of the combustion gas 207 serving as a heat source ofgasification is discharged through the discharge line 235 and the heatexchanger 244 to the outside of the gasification chamber 202. The excessgas (the combustion gas 207) may be utilized as a heat source forincreasing the reaction temperature of a catalyst (i.e., a heat sourcefor heating a catalyst) in a methanol synthesis unit. Alternatively, theexcess gas (the combustion gas 207) may be recovered through a recoveryline (not illustrated) to the combustion space 203 in the combustionchamber 201.

[0495] The residual ash 223 of the biomass 210 combusted in thecombustion space 203 is precipitated and accumulated at the bottom ofthe combustion chamber 201. The precipitated and accumulated ash 223 isintermittently discharged through the discharge line 225 to the outsideof the combustion chamber 201. The residual ash 231 of the biomass 226which is subjected to reaction in the gasification space 204 in thereaction tube 240 is intermittently discharged from the lower portion ofthe reaction tube 240 through the discharge line 233 to the outside ofthe gasification chamber 202.

[0496] As described above, since the gasification furnace according tothe present embodiment has the aforementioned structure, thegasification furnace according to the twenty-seventh embodiment providesoperation and effects similar to those of the gasification furnaceaccording to the twenty-sixth embodiment.

[0497] Particularly, in the gasification furnace according to thetwenty-seventh embodiment, only the steam 245 is fed, as a gasificationagent, to the reaction tube 240 and an oxidizing agent is not necessary,since the gasification space 204 in the reaction tube 240 is separatedfrom the combustion gas feeding passage 206. Since the steam 245contains no oxygen, problems caused by generation of CO₂ can beprevented. In the gasification furnace according to the twenty-seventhembodiment, the biomass 210 for combustion is completely combusted inthe combustion space 203 of the combustion chamber 201, and the cleancombustion gas 207 can be fed to the gasification space 204 in thereaction tube 240. In the gasification furnace according to the presentembodiment, a great difference in form between the biomass 210 forcombustion and the biomass 226 for gasification does not raise anyproblem. For example, wood chips are employed as the biomass 210 forcombustion. In contrast, as the biomass 226 for gasification, biomasspowder having a size of 5-10 mm or less, preferably about 1 mm, isemployed. Alternatively, slurry in which the powder and water are mixedis employed as the biomass 226.

[0498] [Twenty-Eighth Embodiment]

[0499]FIG. 36 schematically depicts a biomass gasification furnaceaccording to Embodiment 28 of the present invention. The gasificationfurnace according to the twenty-eighth embodiment is a modification ofthe gasification furnace according to the twenty-sixth embodiment. InFIG. 36, reference numerals identical with those in FIG. 34 and FIG. 35represent the same components.

[0500] In the biomass gasification furnace, a combustion space 203 and agasification space 204 are separated from each other, and these spacesare provided at the lower and upper portions of a chamber 247. Areaction tube 248 is provided in the chamber 247. The gasification space204 is provided in the reaction tube 248. A combustion gas feedingpassage 249 is provided between the inside wall surface of the chamber247 and the outside wall surface of the reaction tube 248. The reactiontube 248 includes a large number of perforations 250 for uniformlyfeeding the combustion gas 207 from the combustion gas feeding passage249 to the interior of the reaction tube 248. A horizontal-type heatexchanger 251 (heat recovery means and dust removing means) is providedabove the combustion space 203.

[0501] In the chamber 247, the space between the combustion space 203and the combustion gas feeding passage 249 serves as a combustion gasfeeding line.

[0502] A grate 253 having a large number of perforations 252 is providedat the lower portion of the chamber 247. A wind box 254 for feeding anoxidizing agent and steam is provided between the grate 253 and thechamber 247. Feeding hoppers 255 and 256 are provided on a feeding line212 for biomass 210 for combustion and on a feeding line 228 for biomass226 for gasification, respectively. Means for recovering the non-reactedbiomass 226 for gasification is provided between a discharge line 230for a synthesis gas 229 and the reaction tube 248. The means includes acyclone 257, a circulation-feeding valve 258, and a circulation-feedingline 259.

[0503] A line 261 for feeding cooling water 260 is connected to a heatexchanger 244 provided on a discharge line 235 for the combustion gas207. A flow control valve 218 and a feeding line 219 for feeding water217 or steam 220 are provided between the heat exchanger 244 and theheat exchanger 251. A pressure control valve 221 and a feeding line 222for feeding the steam 220 are provided between the heat exchanger 251and the combustion space 203. The feeding line 222 is branched. A branchline 262 of the feeding line 222 is connected through a valve 263 to thewind box 254 for feeding an oxidizing agent and steam, to thereby feedthe steam 220 to the wind box 254.

[0504] Since the biomass gasification furnace according to thetwenty-eighth embodiment has the aforementioned structure, the biomassgasification furnace according to the twenty-eighth embodiment providesoperation and effects similar to those of the biomass gasificationfurnace according to the twenty-sixth and the twenty-seventhembodiments.

[0505] Particularly, according to the twenty-eighth embodiment, theentire structure of the biomass gasification furnace is simplified,since the combustion space 203 and the gasification space 204 areprovided in the chamber 247 while these spaces are separated from eachother. The biomass gasification furnace according to the presentembodiment includes the means 257, 258, and 259 for recoveringnon-reacted biomass for gasification. Therefore, adverse effects ofnon-reacted granular biomass on units provided downstream can beprevented, and fed biomass can be completely gasified.

[0506] [Twenty-Ninth Embodiment]

[0507] FIGS. 37-39 show the methanol production system according to thetwenty-ninth embodiment including the biomass gasification furnace ofthe present invention. In FIGS. 37-39, components denoted by referencenumerals identical with those in FIGS. 34-36 represent the samecomponents.

[0508] In FIGS. 37-39, reference numerals 264, 265, and 266 represent abiomass gasification furnace, gas purification/storage equipment, and amethanol synthesis unit, respectively. The biomass gasification furnace264 is a partially modified version of the biomass gasification furnaceaccording to the twenty-seventh embodiment.

[0509] In the biomass gasification furnace 264, the inner walls of acombustion chamber 201 and a gasification chamber 202 are lined with arefractory material 267. A combustion gas feed line 209 which connects acombustion space 203 in the combustion chamber 201 with a combustion gasfeeding passage 206 in the gasification chamber 202 is also lined withthe refractory material 267, and forms a duct structure.

[0510] At the top of the combustion chamber 201 is provided an opening268 through which biomass 210 for combustion is fed. The opening 268 isprovided with an opening and closing cap 269 via a hinge mechanism 270,such that the opening can be opened or closed. The opening and closingcap 269 is provided with a handle 271 for opening and closing the cap269. The opening and closing cap 269 represented by two-dot lines inFIG. 38 shows an opened position, and the cap 269 represented by solidlines shows a closed position.

[0511] As described above, in the biomass gasification furnace 264 of atype in which the combustion chamber 201 and the gasification chamber202 are provided separately, the opening 268 for feeding and the openingand closing cap 269 are provided in the combustion chamber 201. Thus,substances having a large size rather than being in granular form, suchas wood chips, can be used as the biomass 210 for combustion.

[0512] The opening and closing cap 269 is connected to a feeding line212 for feeding the biomass 210 for combustion via a feeding unit 211,and is connected to a feeding line 215 for feeding an oxidizing agent213 via a feed control valve 214. In the biomass gasification furnace264, the combustion gas feed line 209 and an ignition burner 238 areprovided below a grate 237 of the combustion chamber 201.

[0513] In the gasification chamber 202, a feed hopper 256 for feedingbiomass 226 for gasification, an opening and closing valve 272, afeeding unit (feeding valve) 227, and a feed line 228 are connected to areaction tube 240.

[0514] In the gasification chamber 202, a heat exchanger 243 isinstalled along a discharge line 230 for discharging a synthesis gas229. The heat exchanger 243 includes a water-cooling jacket of dual-tubestructure. The outlet end of the heat exchanger 243 for the synthesisgas 229 is connected to the inlet end of a heat exchanger 244 installedalong a discharge line 235 for discharging a combustion gas 207 via afeed line 246 and a pressure control valve 273.

[0515] In the gasification chamber 202, the outlet end of the heatexchanger 244 for the combustion gas 207 is connected to thegasification chamber 202 (i.e., a lower section of the reaction tube240) via the feeding line 246 and a flow control valve (or a pressurecontrol valve) 274. The flow control valve 274 also regulates thetemperature of heated steam 245 to be fed to the reaction tube 240.

[0516] (Description of Gas Purification/storage Equipment)

[0517] The gas purification/storage equipment 265 includes cleanupequipment 275, a storage tank 276, a booster pump 277, a first openingand closing valve 278, a second opening and closing valve 279, a thirdopening and closing valve 280, and a fourth opening and closing valve281.

[0518] The cleanup equipment 275 includes a dust-removing unit (notillustrated) and a desulfurization unit (not illustrated). ACO₂-removing unit (not illustrated) for removing CO₂ which is notrequired for methanol synthesis from the synthesis gas 229 may beinstalled in the cleanup equipment 275 in accordance with needs.

[0519] A discharge line 230 (i.e., a feeding line 282 for feeding thesynthesis gas 229) for discharging the synthesis gas 229 obtained fromthe biomass gasification furnace 264 is connected to the cleanupequipment 275. The storage tank 276 is connected to the cleanupequipment 275 via the first opening and closing valve 278 and thefeeding line 282. The booster pump 277 is connected to the cleanupequipment 275 via the second opening and closing valve 279 and thefeeding line 282. The booster pump 277 is also connected to the storagetank 276 via the third opening and closing valve 280 and the feedingline 282. The outlet of the booster pump 277 is connected to themethanol synthesis unit 266 via the fourth opening and closing valve 281and the feeding line 282.

[0520] (Description of Methanol Synthesis Unit)

[0521] The methanol synthesis unit 266 includes a pressurizing chamber283, a catalyst chamber 284, and a methanol recovery chamber 285. Thepressurizing chamber 283 and the catalyst chamber 284 are formed withina single chamber, and a partition 286 is provided therebetween. Thepartition 286 is provided with a large number of perforations 287.Therefore, the pressurizing chamber 283 is in communication with thecatalyst chamber 284 via the perforations 287 of the partition 286.

[0522] The catalyst chamber 284 and the methanol recovery chamber 285are connected via a connection line 288. A partition plate 289 having alarge number of perforations is provided between the bottom of thecatalyst chamber 284 and the connection line 288. An opening and closingvalve 290 is provided in the way of the connection line 288. Therefore,the catalyst chamber 284 is in communication with the methanol recoverychamber 285 via the partition plate 289 and the opening and closingvalve 290.

[0523] A pressurizing piston 291 is provided in the pressurizing chamber283. A hydraulic cylinder 292 is connected to the pressurizing piston291. A hydraulic pump 293 is connected to the hydraulic cylinder 292 viaa control valve 294. A pressure detection means 295 is provided in thepressurizing chamber 283. A controlling means 296 for controlling thedriving pressure of the hydraulic cylinder 292 is provided between thepressure detection means 295 and the control valve 294.

[0524] The pressurizing piston 291, the hydraulic cylinder 292, thehydraulic pump 293, the control valve 294, the pressure detection means295, and the controlling means 296 constitute a pressurizing unit. Thepressurizing unit controls the pressure in the pressurizing chamber 283and the catalyst chamber 284 to the optimum pressure for methanol gassynthesis; i.e., 10 to 40 ata.

[0525] The catalyst chamber 284 is filled with a catalyst 297 such as aCuO catalyst or ZnO catalyst. A heating coil 298 is provided in thecatalyst chamber 284, and a heating jacket 299 is provided outside ofthe catalyst chamber 284.

[0526] The discharge line 235, which discharges the combustion gas 207which has passed through the heat exchanger 244 of the biomassgasification furnace 264, is branched into two lines. One of thebranched lines is connected to the inlet of the heating coil 298, andthe other is connected to the inlet of the heating jacket 299. Theoutlet of the heating coil 298 and the outlet of the heating jacket 299are connected to the combustion space 203 of the biomass gasificationfurnace 264 via a recovery line 239. Therefore, the interior temperatureof the catalyst chamber 284 is controlled to an optimum temperature formethanol synthesis; i.e., 200-400° C.

[0527] The feeding line 282 for feeding the synthesis gas fed from thegas purification/storage equipment 265 is connected to the inlet of thecatalyst chamber 284. An opening and closing valve 300 and a dischargeline 301 are connected to the outlet of the catalyst chamber 284.

[0528] A water-cooling jacket 302 is provided outside of the methanolrecovery chamber 285. A feed line for feeding cooling water 308 isconnected to the inlet of the water-cooling jacket 302. The outlet ofthe water-cooling jacket 302 is connected to the inlet of the heatexchanger 243 of the biomass gasification furnace 264 via a pump 304 anda recovery line 303 for returning cooling water. Therefore, the interiortemperature of the methanol recovery chamber 285 is controlled andmaintained at the boiling point of methanol (64.65° C.) or lower.

[0529] An opening and closing valve 307 and a recovery line 306 forrecovering liquid methanol 305 (represented by an outlined broken arrowor a double broken arrow in FIG. 39) are connected to the bottom of themethanol recovery chamber 285.

[0530] Operation of the methanol production unit including the biomassgasification furnace according to the twenty-ninth embodiment and havingthe above-described configuration will be described hereinbelow.

[0531] As described above, the synthesis gas 229 is generated in thebiomass gasification furnace 264. Biomass 210 for combustion iscombusted in the combustion chamber 201 which is separately provided.The combustion gas 207 is utilized as a heat source in the reaction tube240 of the gasification chamber 202, which is installed separate fromthe combustion chamber 201. In the reaction tube 240, the biomass 226for gasification is gasified, to thereby yield the synthesis gas 229.

[0532] Subsequently, the synthesis gas 229 generated in the biomassgasification furnace 264 is fed to the gas purification/storageequipment 265 via the discharge line 230 and the feeding line 282. Thesynthesis gas 229 is purified by means of a purification unit, such as adust-removing unit or a desulfurization unit, in the cleanup equipment275 of the gas purification/storage equipment 265.

[0533] The purified synthesis gas 229 is directly pressurized by thebooster pump 277 via the second opening and closing valve 279, and thepressurized gas is fed to the methanol synthesis unit 266 via the fourthopening and closing valve 281. Alternatively, the purified synthesis gas229 is transferred to the storage tank 276 via the first opening andclosing valve 278 for a temporary storage. After the temporary storage,the gas is fed to the booster pump 277 via the third opening and closingvalve 280 and is pressurized by the booster pump 277. The pressurizedgas is then fed to the methanol synthesis unit 266 via the fourthopening and closing valve 281.

[0534] The capacity of the storage tank 276 and the respective openingand closing operations of the first opening and closing valve 278through the fourth opening and closing valve 281 are determined inaccordance with the sizes and the operation conditions of the biomassgasification furnace 264 and the methanol synthesis unit 266.

[0535] The synthesis gas 229 pressurized in the gas purification/storageequipment 265 is fed to the methanol synthesis unit 266. The synthesisgas 229 is first introduced into the catalyst chamber 284 in themethanol synthesis unit 266, and then introduced into the pressurizingchamber 283 and into the methanol recovery chamber 285. The synthesisgas 229 is introduced in an amount corresponding to the total internalvolume of the catalyst chamber 284, the pressurizing chamber 283, andthe methanol recovery chamber 285 of the methanol synthesis unit 266 ata pressure falling within a range of atmospheric pressure to 10 ata.

[0536] During introduction of the synthesis gas 229 into the catalystchamber 284, the pressurizing chamber 283, and the methanol recoverychamber 285, the opening and closing valve 300 is closed, and thepressurizing piston 291 is located at the upper dead point. Aftercompletion of the introduction, the fourth opening and closing valve 281is also closed so as to prevent the catalyst chamber 284, thepressurizing chamber 283, and the methanol recovery chamber 285 fromcommunicating with the outside.

[0537] Subsequently, the pressurizing unit is initiated to drive. Then,the catalytic reaction of the synthesis gas 229 proceeds by the actionof the catalyst 297 under a predetermined pressure of 10-40 ata and at apredetermined temperature of 200-400° C., to thereby synthesize methanolgas.

[0538] As the methanol gas production proceeds, methanol gas diffusesand flows from the catalytic chamber 284 into the methanol recoverychamber 285 via the perforations in the partition plate 289. In themethanol recovery chamber 285, methanol gas is cooled to a temperatureequal to or lower than the boiling point of methanol (64.65° C.) so asto be liquefied. The liquid methanol 305 is stored in the methanolrecovery chamber 285.

[0539] As the above-described reaction process (i.e., production ofmethanol gas from the synthesis gas 229, and liquefaction of methanolgas to yield the liquid methanol 305) proceeds, partial pressures of H₂and CO gas contained in the synthesis gas 229 is decreased, resulting inpressure drop in the catalyst chamber 284, the pressurizing chamber 283,and the methanol recovery chamber 285. During the reaction process, theabove-described reactions proceed simultaneously. Therefore, the ratio[CH₃OH]/[CO, H₂] remains constant, and thus the reaction[CO]+[2H₂]→CH₃OH proceeds continuously.

[0540] The pressure detection means 295 in the pressurizing chamber 283detects the pressure drop, and the resultant detection signal istransmitted to the controlling means 296. Subsequently, a control signalis transmitted from the controlling means 296 to the control valve 294.As a result, the amount of pressurized oil supplied through thehydraulic pump 293 to the hydraulic cylinder 292 is regulated.Therefore, the pressure of the catalyst chamber 284, the pressurizingchamber 283, and the methanol recovery chamber 285 is controlled tomaintain a predetermined value.

[0541] When the above-described reaction process reaches the finalstage, H₂ and CO gas contained in the synthesis gas 229 are consumed,and the gas becomes a CO₂-rich gas. In other words, the partialpressures of H₂ and CO gas in the synthesis gas 229 decrease, whereasthe partial pressure of CO₂ gas relatively increases. In theabove-described reaction, in general, the relation [CH₃OH]/[H₂],[CO]=0.3-0.5 is satisfied.

[0542] When the above-described reaction process reaches the finalstage, the partial pressure of CO₂ gas increases. However, CO₂ gas doesnot participate in methanol synthesis, and thus CO₂ gas becomes aresidual gas 309. The residual gas 309 contained in the catalyst chamber284, the pressurizing chamber 283, and the methanol recovery chamber 285is purged by opening the opening and closing valve 300, and by closingthe opening and closing valve 290. The liquid methanol 305 recovered inthe methanol recovery chamber 285 is recovered by opening the openingand closing valve 307.

[0543] After a single procedure including introduction of the synthesisgas 229, production of methanol gas, liquefaction of methanol gas,purging of the residual gas 309, and recovery of the liquid methanol 305is completed in the methanol synthesis unit 266, the synthesis gas 229is introduced into the unit again, and the same procedure is repeated.

[0544] As described above, the methanol production unit including thebiomass gasification furnace according to the twenty-ninth embodimentemploys a batch production method for methanol synthesis in the methanolsynthesis unit 266. Thus, a higher ratio of the amount of gas per unitamount of catalyst (i.e., S/V ratio) can be attained. In other words, H₂and CO contained in the synthesis gas can be effectively utilized formethanol (CH₃OH) synthesis. In addition, synthesis of methanol (i.e.,production of methanol gas) and liquefaction of methanol can be carriedout simultaneously in the same unit (methanol synthesis unit 266).Moreover, equipment such as a recirculation line for synthesis gas,which is required for a methanol synthesis unit of continuousproduction, can be omitted, resulting in a simpler structure and asimpler control mechanism.

[0545] The methanol production unit including the biomass gasificationfurnace according to the present embodiment employs the methanolsynthesis unit 266 for batch production, whereas the biomassgasification furnace 264 produces the synthesis gas 229 continuouslythrough continuous operation. However, continuous operation of themethanol production unit as a whole can be attained through temporarystorage in the storage tank 276 of the synthesis gas 229 fed from thebiomass gasification furnace 264.

[0546] In the methanol production unit according to the presentembodiment including a biomass gasification furnace, a heating coil 298and a heating jacket 299 serving as means for heating the catalystchamber 284 are connected to the discharge line 235 provided fordischarging the combustion gas 207 produced in the biomass gasificationfurnace 264, to thereby recycle the waste heat produced in the biomassgasification furnace 264.

[0547] The methanol production unit including the biomass gasificationfurnace according to the twenty-ninth embodiment can recycle the coolingwater 308 which has been used in the methanol synthesis unit 266. Suchrecycling can be attained by means of connecting the water-coolingjacket 302, which serves as a cooling means for the methanol recoverychamber 285, to the heat exchangers 243 and 244 of the biomassgasification furnace 264 via the cooling water recovery line 303.

[0548] The methanol production unit according to the twenty-ninthembodiment employs a modified form of the biomass gasification furnace264 according to the twenty-seventh embodiment. However, the methanolproduction unit of the present invention may employ, a modified form ofthe biomass gasification furnace according to the twenty-sixth ortwenty-eighth embodiment.

[0549] The methanol production unit of the present invention may employa conventional biomass gasification furnace instead of the biomassgasification furnace of the present invention. In other words, themethanol production unit of the present invention may be composed of aconventional biomass gasification furnace and a batch-type methanolsynthesis unit.

[0550] [Thirtieth Embodiment]

[0551] A specific structure of a biomass feeding unit for feedingbiomass to the above-described biomass gasification furnace will next bedescribed.

[0552] Finely pulverized biomass as described above is obtained in theform of aggregated fine particles, each particle having a size of about0.05-1.0 mm, and the particles are formed of complicatedly and denselyentangled fibrous matter. Therefore, when such finely pulverized biomassis fed to a gasification furnace, a particular means is required in afeeding unit for feeding the particles to, for example, a gasificationfurnace.

[0553] As described above, finely pulverized biomass is in the form ofaggregated particles in which very fine fibrous particles are denselyentangled, and thus such particles are easily compressed, resulting infurther complication in the entanglement of particles due tocompression. This causes problematic phenomena that the finelypulverized biomass forms a bridge in the hopper to close the outlet ofthe hopper, and uneven flow of the biomass occurs. In either case,continuous, uniform release of the finely pulverized biomass from thehopper becomes difficult. FIG. 40 depicts examples of such phenomena.

[0554]FIG. 40(A) shows a state in which finely pulverized biomass 11forms a bridge in a hopper 1002 and closes an outlet 1002 a of thehopper. FIG. 40(B) shows the case in which the finely pulverized biomass11 is compressed and entangled in a hopper 1002 to assume a stable formshown in the figure, and thus the flow of the biomass is not uniform orrelease of the biomass through an outlet 1002 a is difficult.

[0555] When finely pulverized biomass is discharged by use of acustomary screw feeder serving as a quantitative feeding machine ofparticles, periodic pulsation of the discharge amount occurs. Dischargeof the finely pulverized biomass will next be described in more detailwith reference to drawings.

[0556]FIG. 41 schematically shows a particle quantitative feedingmachine employing a screw feeder according to a conventional art. Asshown in FIG. 41, a screw feeder 1003 includes a casing 1003 a, which isan elongated box disposed horizontally; and a screw 1003 b which issupported so as to rotate about the horizontal axis of the casing 1003a. The screw 1003 b includes a screw shaft 1003 b ₁ and a screw flight1003 b ₂ which is provided spirally along the axial direction of thescrew shaft 1003 b ₁. In the screw feeder 1003, a substance to beconveyed is constrained between the inner wall surface of the casing1003 a and adjacent walls of the screw flight 1003 b ₂, and thesubstance is conveyed to the end portion of the screw feeder in theaxial direction of the feeder while the screw shaft 1003 b ₁ is rotated.A circular outlet 1003 a ₁ which is opened downward is provided at thelower surface of the end portion of the casing 1003 a. Therefore, thesubstance conveyed to the position of the outlet 1003 a ₁ is dischargeddownward through the outlet 1003 a ₁. In other words, when the substanceconstrained between the inner wall surface of the casing 1003 a andadjacent walls of the screw flight 1003 b ₂ is conveyed to the outlet1003 a ₁ the substance is released from the constraint, and fallsdownward due to gravity.

[0557] When finely pulverized biomass 11 is fed, as a substance to beconveyed, to the screw feeder 1003, the biomass is conveyed anddischarged as shown in FIGS. 42(A) to 42(D). FIGS. 42(A) to 42(D)respectively show the states in which the screw shaft 1003 b ₁ has beenrotated by a 1/4 cycle, a 2/4 cycle, or a 3/4 cycle from the state shownin FIG. 42(A). FIG. 42(A) shows the state in which a portion of thefinely pulverized biomass 11 a constrained and conveyed between a screwflight 1003 b ₂₁ and a screw flight 1003 b ₂₂ is present immediatelybefore an outlet 1003 a ₁. FIG. 42(B) shows the state in which theendmost of the portion 11 a faces the outlet 1003 a ₁. When the screwshaft 1003 b ₁ is rotated, a portion of the portion 11 a of the finelypulverized biomass facing the outlet 1003 a ₁ (the portion of theportion 11 a facing the outlet 1003 a ₁ is represented by light dots inFIG. 42) gradually increases. A large amount of finely pulverizedbiomass is entangled complicatedly in the portion 11 a, since thebiomass is compressed and conveyed by the screw feeder 1003. Therefore,the biomass does not fall through the outlet 1003 a ₁ at the state shownin FIG. 42(C). In the state shown in FIG. 42(D), the aggregation of theportion 11 a breaks by the gravity acting on the portion of the portion11 a facing the outlet 1003 a ₁ and falls downward through the outlet1003 a ₁, and the portion is discharged to the outside. However, thetime when the aggregation breaks cannot be specified. When the force ofgravity acting on the portion of the portion 11 a facing the outlet 1003a ₁ exceeds the force to maintain the aggregation by entanglement of theportion 11 a, the aggregation breaks. However, the time when theaggregation breaks is not determined unconditionally. When the outlet1003 a ₁ has a circular shape, the aggregation may fail to break untilthe state shown in FIG. 42(D).

[0558] When the frequency at which the aggregation of the finelypulverized biomass breaks and falls is smaller and the amount of theaggregation which breaks and falls at a time is larger, pulsation in theamount of the finely pulverized biomass fed from the screw feeder 1003becomes naturally larger. When the line forming the upstream-side edgeportion of the outlet; i.e., the line crossing with the axis of thescrew feeder 1003, is inclined in the inclination direction of the screwflight 1003 b ₂ and at the inclination angle of the screw flight,pulsation in the feed amount of the finely pulverized biomass becomesmaximum. In this case, the shape of a portion of the finely pulverizedbiomass which faces the outlet, the biomass being constrained betweenwalls of the screw flight 1003 b ₂ adjacent to each other, becomes aparallelogram. When the area of the parallelogram increases inproportion to the distance that the screw flight 1003 b ₂ moves in theaxial direction in accordance with rotation of the screw shaft 1003 b ₁,a large amount of the aggregation of the finely pulverized biomassbreaks as soon as the force to maintain the aggregation by entanglementbecomes less than the force exerted by gravity. When the inclinationangle of the line forming the upstream-side edge portion of the outletis brought to be nearly perpendicular with respect to the axis of thescrew feeder 1003, the probability of the aggregation of the finelypulverized biomass facing the outlet will break gradually increases, andthus the amount of the finely pulverized biomass falling through theoutlet may be averaged. However, in consideration that if the finelypulverized biomass is employed as a raw material for gasification thebiomass must be continuously fed to a gasification furnace and the feedamount must be uniform, the angle of the line forming the edge portionmust be the same as that of a straight line perpendicular to the axis ofthe screw feeder 1003. As described above, when the line forming theupstream-side edge portion of the outlet is perpendicular to the axis ofthe screw feeder 1003, the frequency at which the aggregation of thefinely pulverized biomass breaks and falls increases, as compared withthe conventional case in which the shape of the outlet 1003 a ₁ iscircular. As a result, the aggregation of the biomass continuously fallsthrough the outlet.

[0559] When the angle of the line forming the upstream-side edge portionof the outlet is gradually inclined from the angle of the lineperpendicular to the axis of the screw feeder 1003 to the angle oppositethe inclination angle of the screw flight 1003 b ₂, in accordance withan increase in the angle of the line, the frequency at which theaggregation of the finely pulverized biomass breaks and falls mayincrease and the amount of the aggregation which breaks and falls at atime may decrease. This is because the finely pulverized biomass betweenadjacent walls of the screw flight 1003 b ₂ can be gradually caused toface the outlet. Therefore, theoretically, when the line forming theupstream-side edge portion of the outlet is inclined to the oppositedirection to the inclination direction of the screw flight 1003 b ₂ atthe inclination angle of the flight with respect to the lineperpendicular to the axis of the screw feeder 1003, the amount of thefinely pulverized biomass which is fed can be averaged, the biomassbeing fed through breakage of the aggregation of the biomass.

[0560] As described above, in the case of the screw feeder 1003according to the conventional art, the outlet 1003 a ₁ has a circularshape, and thus the frequency at which the portion 11 a of the finelypulverized biomass 11 breaks and falls is small and pulsation in thefeed amount of the biomass easily occurs. Such pulsation is a fataldefect of apparatus for feeding a raw material to a gasificationfurnace. This is because a raw material must be continuously fed to agasification furnace, and the amount of the raw material fed to thefurnace must be uniform.

[0561] In the case of the aforementioned screw feeder 1003, constraintof the conveyed finely pulverized biomass 11 is released at only oneportion; i.e., at the outlet 1003 a ₁. Therefore, pulsation in the feedamount of the biomass easily occurs.

[0562] In this case, techniques in relation to coal micropowder feedingunit which has been conventionally employed as a feeding unit of a coalgasification furnace cannot be applied to the aforementionedgasification furnace system in which finely pulverized biomass isemployed as a raw material. Therefore, there has been demand fordeveloping, on the basis of a completely novel concept, feeding unit forfeeding finely pulverized biomass to a gasification furnace uniformlyand continuously.

[0563]FIG. 43 schematically shows a biomass feeding unit according to athirtieth embodiment of the present invention. FIG. 43(A) is a side viewof the feeding unit; and FIG. 43(B) is a plan view of the feeding unit.

[0564] As shown in FIGS. 43(A) and 43(B), a hopper 1012 is a cylindricalmember for storing finely pulverized biomass which assumes the form offibrous granules obtained by pulverizing biomass. A stirring apparatus1014 is provided in the hopper 1012 for stirring the finely pulverizedbiomass stored in the hopper 1012 to thereby eliminate compression andentanglement of particles of the finely pulverized biomass. The stirringapparatus 1014 includes a perpendicular rod 1014 a and a plurality ofrods 1014 b which are provided horizontally on a plurality of positionsof the rod 1014 a. When the rod 1014 is rotated by a motor 1016, therods 1014 b are rotated on a horizontal plane to thereby stir the finelypulverized biomass.

[0565] A screw feeder 1013 is provided at the lower portion of thehopper 1012. Finely pulverized biomass is conveyed horizontally throughthe screw feeder 1013, and the biomass is discharged downward through anoutlet 1013 a ₁ provided at the distal end of a casing 1013 a. When thefinely pulverized biomass is stirred with the stirring apparatus 1014 inthe hopper 1012, the biomass is continuously fed to the screw feeder1013, and thus the biomass can be smoothly removed from the hopper 1012.

[0566] The screw feeder 1013 includes the casing 1013 a, which is anelongated box provided horizontally, a portion of the casing beinginserted into the lower portion of the hopper 1012; and a screw 1013 bwhich is supported so as to rotate about the horizontal axis of thecasing 1013 a. The screw 1013 b includes a screw shaft 1013 b ₁ and ascrew flight 1013 b ₂ which is provided spirally along the axialdirection of the screw shaft 1013 b ₁, and the screw 1013 b is rotatedby a motor 1051. Therefore, in the screw feeder 1013, the finelypulverized biomass is constrained between the inner wall surface of thecasing 1013 a and adjacent walls of the screw flight 1013 b ₂, and thebiomass is conveyed to the distal end of the screw feeder along theaxial direction of the feeder while the screw shaft 1013 b ₁ is rotated.

[0567] A large-diameter portion 1013 c having a size larger than that ofthe remaining portion is provided at the distal end of the casing 1013 aalong the axial direction of the screw feeder 1013. As a result, thefinely pulverized biomass, which is compressed and constrained betweenadjacent walls of the screw flight 1013 b ₂ and conveyed through thescrew feeder, is released from the constraint at a stretch when thebiomass faces the large-diameter portion 1013 c. The biomass is releasedfrom the constraint over the entire circumference of the large-diameterportion 1013 c. Therefore, in contrast to the case in which fibrousparticles are released through one outlet provided at the lower portionof the casing 1003 a of the screw feeder 1003 according to theconventional art shown in FIG. 41, the biomass is released from thecompressed and entangled state over the entire circumference of thelarge-diameter portion, and the probability that the aggregation of thebiomass breaks and falls by the force of the gravity increases. Briefly,the aggregation of the finely pulverized biomass breaks continuously.

[0568] The outlet 1013 a ₁ for discharging the conveyed finelypulverized biomass is provided at the lower portion of thelarge-diameter portion 1013 c, and the horizontal cross-section of theoutlet 1013 a ₁ assumes a quadrangle. On the side where the base portionof the screw feeder 1013 is present (the hopper 1012 side), the outlet1013 a ₁ has a side crossing the axis of the screw feeder 1013. The sideis a straight line perpendicularly intersecting the axis direction ofthe screw feeder 1013. Therefore, the frequency at which the aggregationof the finely pulverized biomass breaks and falls increases, as comparedwith the case in which the outlet 1003 a ₁ is formed into a circularshape as described in the conventional art shown in FIG. 41. Briefly,the aggregation of the biomass breaks continuously.

[0569] The aggregation of the finely pulverized biomass which isdischarged and falls through the outlet 1013 a ₁ is received by afluidization cone 1017, and a gyratory flow of gas is added to theaggregation, to thereby eliminate entanglement of the fibrous particles.Through use of gas forming the gyratory flow, the fluidization conesupplies a carrier gas for carrying the finely pulverized biomass to adestination apparatus, such as a gasification furnace, through a feedingline 1018. In the fluidization cone 1017, the falling finely pulverizedbiomass is disentangled by the gyratory flow, and fibrous particles ofthe biomass are each individually fed to the feeding line 1018. Ingeneral, when a raw material is fed to a gasification furnace, thedensity of the raw material is increased as much as possible, and theraw material must be fed to the furnace continuously and uniformly.Therefore, the feeding line 1018 is formed of a tube having a diameterreduced to a possible extent, and the density of the raw material ismaintained at a high level by a carrier gas stream which flows at a highrate. Since entanglement of the finely pulverized biomass particlesimmediately causes clogging of the feeding line 1018, the biomass mustbe fed through the line such that entanglement of the biomass iseliminated.

[0570]FIG. 44 is a longitudinal cross-sectional view showing a specificexample of the fluidization cone 1017 shown in FIG. 43 according to thethirtieth embodiment. As shown in FIG. 44, a plurality of injectionnozzles 1019 and 1020 are radially provided on the fluidization cone1017 at positions of two levels in height. Gas is injected from theinjection nozzles 1019 and 1020 toward the mass of aggregated finelypulverized biomass falling through the opening located above. A portionhaving a downwardly reduced diameter is provided at the lower portion ofthe fluidization cone 1017, and the cone 1017 is connected, via the endof the portion, to the feeding line 1018 having a small diameter.

[0571]FIG. 45 is a longitudinal cross-sectional view showing anotherexample of the fluidization cone 1017 according to the thirtiethembodiment shown in FIG. 43. As shown in FIG. 45, a fluidization cone1017A includes a stirring apparatus in addition to the fluidization cone1017 shown in FIG. 44. A horizontal rod 1021 is provided at the centralportion of the fluidization cone 1017A, and a plurality of stirring bars1022 are provided on the rod 1021 so as to form a comb-like shape. Whenthe rod 1021 is rotated by a motor 1023, the stirring bars 1022 arerotated about the rod 1021, to thereby disentangle the fallingaggregation of the finely pulverized biomass.

[0572] The aggregation of the finely pulverized biomass can besufficiently disentangled by the fluidization cone 1017 shown in FIG.44, but the aggregation is disentangled more reliably by thefluidization cone 1017A according to this example. According to thefluidization cone 1017A, even when the gyratory flow is relatively weak,the aggregation of the finely pulverized biomass can be formed intodiscrete, fibrous particles.

[0573] As described above, according to the feeding unit of thethirtieth embodiment, the frequency at which the aggregation of thefinely pulverized biomass facing the outlet 1013 a ₁ breaks increases,whereby the biomass can be continuously fed to the fluidization cone.Accordingly, the amount of the finely pulverized biomass falling to thefluidization cone 1017 is averaged, and uniform fibrous particles of thefinely pulverized biomass can be fed to a destination apparatus such asa gasification furnace, in a continuous manner and with suppressedpulsation in the feed amount of the biomass.

[0574] In the thirtieth embodiment, the outlet 1013 a ₁ is formed tohave a quadrangular shape having a line perpendicular to the axis of thescrew feeder 1013, so as to facilitate production of the large-diameterportion 1013 c. When the facilitation of production is disregarded, theshape of the outlet 1013 a ₁ may be determined as follows. When the lineforming the edge portion of the outlet 1013 a ₁ is inclined in adirection opposite the inclination direction of the screw flight 1013 b₁, with respect to the line perpendicular to the axis of the screwfeeder 1013, at an angle equal to the angle between the screw flight1013 b ₁ and the line perpendicular to the axis of the screw feeder1013, the aggregation of the finely pulverized biomass breaks at thehighest probability. In this case, the feed amount of the finelypulverized biomass can be averaged to the greatest extent.

[0575] [Thirty-First Embodiment]

[0576]FIG. 46 schematically depicts a biomass feeding unit according toa thirty-first embodiment of the present invention. FIG. 46(A) is a sideview of the unit, and FIG. 46(B) is a plan view of the unit. In FIG. 46,reference numerals identical with those in FIG. 43 represent the sameelements, and repeated description of such elements is omitted.

[0577] The thirty-first embodiment differs from the thirtieth embodimentin that, when the finely pulverized biomass is discharged from the screwfeeder 1013, the compressed and entangled biomass is disentangled, tothereby discharge the resultant fibrous particles of the biomass asdiscrete, individual particles through the outlet 1013 a ₁. Therefore,the screw feeder 1013 includes, at its tip portion, gas injection meansfor injecting gas to the finely pulverized biomass (not shown in FIG.46, described below in detail). A funnel-shaped portion 1027 is providedso as to receive the falling finely pulverized biomass discharged fromthe screw feeder 1013. The funnel-shaped portion 1027 receives thefalling finely pulverized biomass discharged through the outlet 1013 a₁. In the funnel-shaped portion 1027, the path of the biomass isgradually narrowed. The biomass is fed through the funnel-shaped portion1027 to the feeding line 1018 connected to a destination apparatus suchas a gasification furnace, and the aforementioned carrier gas for thefinely pulverized biomass is fed by the portion 1027. Through use of thefunnel-shaped portion 1027, clogging of the feeding line 1018 having asmall diameter can be prevented, and the finely pulverized biomass canbe smoothly fed to the destination apparatus.

[0578]FIG. 47 shows an example of a tip portion of the screw feedershown in FIG. 46 according to the thirty-first embodiment. FIG. 47(A) isa longitudinal cross-sectional view of the tip portion, and FIG. 47(B)is a right side view of the tip portion. As shown in FIGS. 47(A) and47(B), injection nozzles 1028 are dispersedly provided on the peripheryof a large-diameter portion 1013 c, and gas is injected through eachnozzle 1028 to the finely pulverized biomass which is constrainedbetween walls of the screw flight 1013 b ₂ and is conveyed through thescrew feeder. The flow of the gas is directed along the flow directionof the biomass conveyed through a conveying path formed between adjacentwalls of the screw flight 1013 b ₂. This is because, -when the flowdirection of the gas is determined as described above, the injected gasis most efficiently supplied to the biomass, and thus the biomass iseffectively disentangled. A plurality of injection nozzles 1029 areprovided at the upper portion of the funnel-shaped portion 1027. Theinjection nozzles 1029 are provided such that gas is injected downward.The flow of a carrier gas for conveying the finely pulverized biomass isformed by the nozzles 1029.

[0579]FIG. 48 shows a longitudinal cross-sectional view of anotherexample of a tip portion of the screw feeder according to thethirty-first embodiment shown in FIG. 46. As shown in FIG. 48, accordingto this embodiment, a screw shaft 1013 b ₁ is formed of a hollow member,and a plurality of perforations 1013 b ₁₁ which penetrate the screwshaft 1013 b ₁ from the outer surface to the interior thereof areprovided between adjacent walls of the screw flight 1013 b ₂ in thevicinity of the endmost portion of the shaft 1013 b ₁, to thereby injectgas to the compressed finely pulverized biomass which is constrainedbetween the walls of the screw flight 1013 b ₂ and conveyed through thescrew feeder. Through use of the screw feeder, compression andentanglement of the biomass is loosened or eliminated, and the resultantfibrous particles of the biomass are discharged as separate, individualparticles, through an outlet 1013 a ₁ downward.

[0580] In this case, the direction of gas flow; i.e., the direction ofthe perforation 1013 b ₁₁, is determined such that the perforation isdirected to oppose the direction along which the biomass is conveyedthrough a conveying path formed between adjacent walls of the screwflight 1013 b ₂. This is because, when the direction of the gas flow isdetermined as described above, the gas is most efficiently applied tothe biomass, and thus the biomass is effectively disentangled anddisintegrated. Through the perforations 1013 b ₁₁, gas is injectedobliquely and upward, to thereby eliminate entanglement of the finelypulverized biomass. The perforations 1013 b ₁₁ are preferably providedat a position one or two pitches distant from the endmost portion of thescrew shaft 1013 b ₁. This is because compression and entanglement ofthe finely pulverized biomass must be eliminated before the finelypulverized biomass reaches the endmost portion of the screw shaft 1013 b₁.

[0581] The above-described function is also realized by providinginjection nozzles in the perforation 1013 b ₁₁ and by controlling thedirection of gas jetted from the nozzles.

[0582] As described above, according to the thirty-first embodiment,when the finely pulverized biomass is discharged from the screw feeder1013, the biomass is formed into separate, independent particles.Therefore, the resultant biomass particles can be smoothly fed throughthe feeding line to a destination apparatus such as gasification furnaceby only narrowing the path of the particles in the funnel-shaped portion1027.

[0583] In the first and the thirty-first embodiments, the pitch betweenthe walls of the screw flight 1013 b ₂ is not described. The pitchesbetween the walls of the screw flight 1013 b ₂ are not necessarily equalto one another. The screw flight 1013 b ₂ must have a sealing function,in order to prevent reverse flow of a carrier gas. In consideration ofprevention of the reverse flow of the gas, the pitch between walls ofthe screw flight 1013 b ₂ is preferably small. In contrast, in order toefficiently discharge the finely pulverized biomass from the end of thescrew feeder, the pitch between the walls of the screw flight 1013 b ₂is preferably large. Therefore, in order to prevent the reverse flow ofa carrier gas and to discharge the biomass efficiently from the screwfeeder, relatively large pitches are provided between adjacent walls ofthe screw flight 1013 b ₂ at the distal end portion of the screw shaft1013 b ₁, and relatively small pitches are provided between adjacentwalls of the screw flight 1013 b ₂ at the central portion of the screwshaft 1013 b ₁, the central portion being adjacent to the distal endportion. In this case, the conveyed finely pulverized biomass isreleased effectively at the distal end portion of the screw shaft 1013 b₁ at which the pitch is large, and gas is effectively sealed at thecentral portion at which the pitch is small.

[0584] The above-described function can also be realized by graduallyreducing the pitches between adjacent walls of the screw flight 1013 b ₂from the base end portion located on the hopper 1012 side to the centralportion at which the pitches are minimum, and by gradually increasingthe pitches from the central portion to the distal end portion of thescrew feeder.

[0585] In the above-described embodiments, the case in which the finelypulverized biomass is employed as granular material is described.However, the present invention is not limited to the above embodiments.When granular material exhibiting characteristics similar to those ofthe biomass is employed, similar effects are obtained. The destinationapparatus of such material is not particularly limited to a gasificationfurnace. For example, the granular material may be fed to a combustionunit.

[0586] [Thirty-Second Embodiment]

[0587]FIG. 49 schematically depicts a biomass feeding unit according tothe thirty-second embodiment of the present invention. FIG. 49(A) is aside view of the feeding unit, and FIG. 49(B) is a plan view of thefeeding unit. As shown in FIGS. 49(A) and 49(B), a hopper 1012 is acylindrical member for storing finely pulverized biomass which is in theform of fibrous granular material obtained by finely pulverizingbiomass. A stirring apparatus 1014 is provided in the hopper 1012 forstirring the finely pulverized biomass stored in the hopper 1012 tothereby loosen compression and eliminate entanglement of particles ofthe biomass. The stirring apparatus 1014 includes a vertical rod 1014 ahaving a plurality of horizontal rods 1014 b provided at a plurality ofpositions of the rod. When the rod 1014 is rotated by a motor 1016, therods 1014 b are rotated in a horizontal plane, to thereby stir thefinely pulverized biomass.

[0588] A screw feeder 1013 is provided at the lower portion of thehopper 1012. The finely pulverized biomass is conveyed horizontallythrough the screw feeder 1013. The diameter of the tip portion of thescrew feeder is gradually decreased, and the end of the screw feeder isconnected to a feeding line 1051 having a small diameter. Morespecifically, the screw feeder 1013 includes a casing 1013 a which is alateral box provided horizontally, a portion of the casing beinginserted into the lower portion of the hopper 1012; and a screw 1013 bwhich is supported so as to rotate about the horizontal axis of thecasing 1013 a. The screw 1013 b includes a screw shaft 1013 b ₁ andwalls of the screw flight 1013 b ₂ which are provided spirally along theaxis direction of the screw shaft 1013 b ₁, and the screw 1013 b isrotated by a motor 1016. In the screw feeder 1013, the finely pulverizedbiomass is constrained between the inner wall surface of the casing 1013a and adjacent walls of the screw flight 1013 b ₂, and the biomass isconveyed to the end of the screw feeder along the axial direction of thefeeder while the screw shaft 1013 b ₁ is rotated.

[0589] At the tip portion of the screw feeder 1013, gas is injected tothe finely pulverized biomass which is compressed and conveyed throughthe screw feeder 1013, to thereby loosen compression and eliminateentanglement of the biomass to form independent, discrete fibrousparticles (the structure in relation to the above is not illustrated,and will be described in detail with reference to FIG. 50). Through useof a carrier gas stream of the above gas, the resultant fibrousparticles are conveyed through the feeding line 1051 and fed to adestination apparatus such as a gasification furnace.

[0590]FIG. 50(A) is a longitudinal cross-sectional view showing a firstexample of the structure of a tip potion of the screw feeder shown inFIG. 49 according to the present embodiment. As shown in FIG. 50(A),according to the first example of this embodiment, a screw shaft 1013 b₁ whose distal end portion has a spire shape is formed of a hollowmember, and a plurality of perforations 1013 b ₁₁ which penetratethrough the shaft 1013 b ₁ are provided between adjacent walls of thescrew flight 1013 b ₂ in the vicinity of the frontmost end portion ofthe shaft 1013 b ₁, to thereby inject gas through the perforations 1013b ₁₁ to the compressed finely pulverized biomass which is constrainedbetween adjacent walls of the screw flight 1013 b ₂ and conveyed throughthe screw feeder. Through use of the screw feeder, the finely pulverizedbiomass is blown to the tip portion of feeder, and the biomass isreleased from constraint between the walls of the screw flight 1013 b ₂,compression and entanglement of the biomass is loosened and eliminated,and the resultant fibrous particles of the biomass are fed, asindependent, discrete particles, to the feeding line 1051. The gasapplied to the biomass is employed as a carrier gas, and the biomassfibrous particles are accompanied by the carrier gas and fed to adestination apparatus. The direction of gas flow; i.e., the direction ofthe perforation 1013 b ₁₁, is determined such that the perforation isdirected to the direction that the biomass is conveyed through aconveying path formed between adjacent walls of the screw flight 1013 b₂. This is because, when the direction of the gas flow is determined asdescribed above, the gas is most efficiently applied to the biomass, andthus compression and entanglement of the biomass is effectivelyeliminated. Through the perforations 1013 b ₁₁, gas is injectedobliquely and upward, to thereby loosen compression and eliminateentanglement of the finely pulverized biomass. The perforations 1013 b₁₁ are preferably provided at a position one or two pitches distant fromthe frontmost end portion of the screw shaft 1013 b ₁. This is becausecompression and entanglement of the finely pulverized biomass must beeliminated before the frontmost end portion of the screw shaft.

[0591] The above-described function is also realized by providinginjection nozzles in the perforations 1013 b ₁₁ and by controlling thedirection of gas injected via the nozzles.

[0592] As described above, according to the thirty-second embodiment,when the finely pulverized biomass is discharged from the screw feeder1013, the biomass is formed into discrete, independent particles, andthus the resultant biomass particles can be smoothly fed, by a carriergas stream, through the feeding line 1051 to a destination apparatussuch as a gasification furnace.

[0593] In the thirty-second embodiment, since the area of the crosssection of the path of injection gas is defined by a adjacent walls ofthe screw flight 1013 b ₂ and the inner wall surface of the casing 1013a, it is possible to reduce the area of the cross section. When the areaof the cross section is smaller, the higher flow rate of the injectiongas is attained easily. Therefore, the amount of the gas serving as acarrier gas can be reduced to the greatest possible extent. When theamount of the carrier gas is smaller, the content of the raw material(i.e., the finely pulverized biomass) can be increased. As a result, thescrew feeder has a considerable advantage as a raw material feeding unitfor a gasification furnace.

[0594]FIG. 50(B) is a longitudinal cross-sectional view showing a secondexample of the structure of a tip portion of the screw feeder shown inFIG. 49 according to the present embodiment. As shown in FIG. 50(B),provision of walls of the screw flight 1013 b ₂ is ended in the vicinityof the base of the spire-shaped distal end portion of a screw shaft 1013b ₁, and the finely pulverized biomass conveyed to the distal endportion of the screw shaft is released from constraint by the walls ofthe screw flight 1013 b ₂ at the base of the distal end portion. Aplurality of injection nozzles 1052 are dispersedly provided on theperiphery of the distal end portion of a casing 1013 a, and gas isinjected via each injection nozzle 1052 to the finely pulverized biomassimmediately after the biomass is released from constraint by the wallsof the screw flight 1013 b ₂. The direction of the gas flow isdetermined to the axial direction of the screw shaft 1013 b ₁ and afeeding line 1051. This is because, when the direction of the gas flowis determined as described above, the gas is most efficiently applied tothe biomass, and thus compression and entanglement of the biomass iseffectively eliminated, and the resultant biomass particles can becarried by a carrier gas most effectively.

[0595] As described above, according to the second example, when thefinely pulverized biomass is discharged from the screw feeder 1013, thebiomass is formed into independent, discrete particles, and thus theresultant biomass particles can be smoothly fed, on a carrier gasstream, through the feeding line 1051 to a destination apparatus such asa gasification furnace.

[0596] In this example, the area of the cross section of the path ofinjection gas is the area of a circular portion formed between thecross-sectional inner circle of the casing 1013 a and thecross-sectional outer circle of the distal end portion of the screwshaft 1013 b ₁. Since the area of the cross section is larger than thatof the cross section in the case shown in FIG. 50(A), the amount of gasto be supplied increases. However, since the injection nozzles 1052 canbe merely provided from the outside of the casing 1013 a, the structureof the screw feeder can be simplified.

[0597] The pitches between the walls of the screw flight 1013 b ₂ arenot necessarily equal to one another. The screw flight 1013 b ₂ musthave a sealing function, in order to prevent reverse flow of a carriergas. In consideration of prevention of reverse flow of the gas, thepitch between the walls of the screw flight 1013 b ₂ is preferablysmall. In contrast, in order to efficiently carry out release of thefinely pulverized biomass at the tip portion of the screw feeder, thepitch between the walls of the screw flight 1013 b ₂ is preferablylarge. Therefore, in order to prevent reverse flow of a carrier gas andto carry out release of the biomass at the tip portion of the screwfeeder, relatively large pitches are provided between adjacent walls ofthe screw flight 1013 b ₂ at the distal end portion of the screw shaft1013 b ₁, and relatively small pitches are provided between adjacentwalls of the screw flight 1013 b ₂ at the central portion of the screwshaft 1013 b ₁, the central portion being adjacent to the distal endportion. In this case, the conveyed finely pulverized biomass can bereleased effectively at the distal end portion of the screw shaft 1013 b₁ at which the pitch is large, and gas sealing can be effectivelycarried out at the central portion at which the pitch is small.

[0598] The above-described function can also be realized by graduallyreducing the pitches between adjacent walls of the screw flight 1013 b ₂from the side of the hopper 1012 to the central portion at which thepitches are minimum, and by gradually increasing the pitches from thecentral portion to the tip portion of the screw feeder.

[0599] In the above-described embodiment, the case in which the finelypulverized biomass is employed as granular material is described.However, the present invention is not limited to the above embodiment.When granular material exhibiting characteristics similar to those ofthe biomass is employed, similar effects are obtained. The destinationapparatus of such material is not particularly limited to a gasificationfurnace. For example, the granular material may be fed to a combustiontreatment unit.

[0600] Industrial Applicability

[0601] As described hereinabove, a suitable application of the presentinvention includes a biomass gasification furnace exhibiting clean andhighly efficient gasification, attaining complete gasification ofbiomass, and producing a gas for a highly efficient methanol synthesis;and a methanol synthesis system making use of the produced gas.

1. A methanol synthesis system making use of biomass, characterized bycomprising: a biomass gasification furnace for gasifying biomass; a gaspurification unit for purifying gas generated through gasificationperformed in the biomass gasification furnace; and a methanol synthesisunit for synthesizing methanol from H₂ and CO contained in the resultantpurified gas; wherein the biomass gasification furnace comprises meansfor feeding pulverized biomass having an average particle size (D)falling within a range of 0.05≦D≦5 mm andcombustion-oxidizing-agent-feeding means for feeding oxygen or a mixtureof oxygen and steam serving as a combustion-oxidizing agent, wherebygasification of the biomass is performed under gasification conditionsthat the mol ratio of oxygen [O₂]/carbon [C] in the biomass gasificationfurnace falls within a range of 0.1≦O₂/C<1.0, the mol ratio of steam[H₂O]/carbon [C] falls within a range of 1≦H₂O/C; and the temperature ofthe interior of the furnace is 700-1,200° C.
 2. A methanol synthesissystem making use of biomass according to claim 1, further comprising,on the upstream side of the methanol synthesis unit, a CO shift reactionunit for adjusting the compositional ratio of H₂ to CO gas contained ina gas.
 3. A methanol synthesis system making use of biomass according toclaim 1, further comprising a carbon dioxide removal unit provided onthe upstream side of the methanol synthesis unit.
 4. A methanolsynthesis system making use of biomass according to claim 1, wherein theinternal pressure of the biomass gasification furnace is 1-30 atm, andgasification conditions include a superficial velocity of 0.1-5 m/s. 5.A methanol synthesis system making use of biomass according to claim 1,wherein the combustion-oxidizing agent is fed to a plurality of stagesin the biomass gasification furnace.
 6. A methanol synthesis systemmaking use of biomass according to claim 1, wherein fossil fuel is fedinto the biomass gasification furnace.
 7. A methanol synthesis systemmaking use of biomass according to claim 1, wherein biomass and acombustion-oxidizing agent are fed into the biomass gasification furnacesuch that the compositional ratio H₂/CO of the generated gas approaches2.
 8. A methanol synthesis system making use of biomass according toclaim 1, wherein steam serving as the combustion-oxidizing agent ishigh-temperature steam of at least 300° C.
 9. A methanol synthesissystem making use of biomass according to claim 1, further comprisingsteam reforming means provided in the vicinity of an upper outlet of thebiomass gasification furnace or on the downstream side of thegasification furnace.
 10. A methanol synthesis system making use ofbiomass according to claim 1, further comprising feeding means forfeeding biomass provided at a top section of a gasification furnace mainbody, and an ash receiving section provided in a bottom section of thegasification furnace main body.
 11. A methanol synthesis system makinguse of biomass according to claim 10, further comprising a gas dischargetube provided at a lower portion of a side wall of the gasificationfurnace main body so as to discharge gas produced through gasification.12. A methanol synthesis system making use of biomass according to claim10, further comprising hollow cylindrical gas-ash introducing meanshaving a downwardly reduced diameter and provided on an inner wallsurface of the gasification furnace in the vicinity of the upper sectionof the gas discharge tube of the gasification furnace.
 13. A methanolsynthesis system making use of biomass according to claim 10, furthercomprising a gas discharge tube for discharging produced gas provided atthe center of a top section of the biomass gasification furnace, the gasdischarge tube extending vertically such that a lower end portion of apredetermined length of the gas discharge tube is inserted into theinterior of the gasification furnace with the lower-end opening of thegas discharge tube facing the interior of the furnace.
 14. A methanolsynthesis system making use of biomass according to claim 10, whereinthe diameter of a lower half portion of the gasification furnace mainbody is slightly reduced as compared with the diameter of an upper halfportion of the main body; a partition is provided vertically in theinterior of the diameter-reduced portion of the gasification furnacemain body, thereby forming a path for introducing produced gas and ash;the produced gas and ash are caused to pass through the path; and theproduced gas is forced to turn at a frontal edge of the partition,thereby removing the ash and discharging the produced gas from the gasdischarge tube.
 15. A methanol synthesis system making use of biomassaccording to claim 7, further comprising: heat exchanging means forremoving steam contained in purified gas; and a CO shift reaction unitfor adjusting the compositional ratio of H₂ to CO gas contained in thepurified gas.
 16. A methanol synthesis system making use of biomassaccording to claim 15, further comprising, on an upstream side of themethanol synthesis unit, a carbon dioxide removal unit for removing CO₂in produced gas.
 17. A methanol synthesis system making use of biomassaccording to claim 1, wherein the biomass gasification furnace and themethanol synthesis unit are mounted on a base or a traveling carriage soas to enable conveyance or transportation.
 18. A methanol synthesissystem making use of biomass according to claim 15, wherein waterdischarged from the heat exchanging means is converted to heated steam,by recovering heat generated during the course of methanol synthesis bythe employment of the methanol synthesis unit and heat from a gasproduced in the biomass gasification furnace; and said heated steam issupplied to the biomass gasification furnace.
 19. A methanol synthesissystem making use of biomass according to claim 18, further comprisingan adsorption column or a guard column inserted between a booster unitand a regenerator and/or between the regenerator and the methanolsynthesis unit.
 20. A methanol synthesis system making use of biomassaccording to claim 18, wherein the methanol synthesis unit is asynthesis column comprising a plurality of stages of catalyst layers,and at least two series of the synthesis columns are provided.
 21. Amethanol synthesis system making use of biomass according to claim 20,wherein the catalyst layer placed on an inlet side of the synthesiscolumn serves as a guard column, and, during synthesis of methanol, afirst synthesis column and a second synthesis column are usedalternately, and when one synthesis column is in use, among a pluralityof stages of catalyst layers in the other synthesis column, thefirst-stage catalyst layer on a gas inlet side is removed, the second-and subsequent-stage catalyst layers are sequentially moved to serve asthe first- and subsequent-stage catalyst layers, and a new additionalcatalyst layer is inserted so as to be placed at the position of thefinal stage.
 22. A methanol synthesis system making use of biomassaccording to claim 18, wherein the recovered heat generated during thecourse of production of methanol is utilized for drying biomass.
 23. Amethanol synthesis system making use of biomass according to claim 1,wherein the biomass gasification furnace comprises a combustion spacefor combusting the biomass and a gasification space for gasifying thebiomass, the spaces being provided separately, and a combustion gasfeeding line for feeding the combustion gas from the combustion space tothe gasification space is provided between the combustion space and thegasification space; and the methanol synthesis unit comprises apressurizing chamber, a catalyst chamber, and a methanol recoverychamber, and operates such that the synthesis gas introduced from thebiomass gasification furnace into the pressurizing chamber, the catalystchamber, and the methanol recovery chamber is pressurized at apredetermined pressure, to thereby transform the synthesis gas intomethanol through catalytic reaction in the catalyst chamber, themethanol is liquefied in the methanol recovery chamber, and theliquefied methanol is recovered and the residual gas is purged.
 24. Amethanol synthesis system making use of biomass according to claim 23,wherein the combustion space and the gasification space are provided inseparately disposed combustion and gasification chambers, respectively;a reaction tube is provided in the gasification chamber; thegasification space is provided in the reaction tube; a combustion gasfeeding passage connected to the combustion gas feeding line is providedbetween the inside wall surface of the gasification chamber and theoutside wall surface of the reaction tube; and perforations foruniformly feeding the combustion gas from the combustion gas feedingpassage to the reaction tube are provided in the reaction tube.
 25. Amethanol synthesis system making use of biomass according to claim 23,wherein the combustion space and the gasification space are provided inseparately disposed combustion and gasification chambers, respectively;a reaction tube is provided in the gasification chamber; thegasification space is provided in the reaction tube; and a combustiongas feeding passage connected to the combustion gas feeding line isprovided between the inside wall surface of the gasification chamber andthe outside wall surface of the reaction tube.
 26. A methanol synthesissystem making use of biomass according to claim 23, wherein thecombustion space and the gasification space are provided in a singlechamber in such a manner that the combustion space and the gasificationspace are separated from each other; a reaction tube is provided in thesingle chamber; the gasification space is provided in the reaction tube;a combustion gas feeding passage connected to the combustion gas feedingline is provided between the inside wall surface of the chamber and theoutside wall surface of the reaction tube; and perforations foruniformly feeding the combustion gas from the combustion gas feedingpassage into the reaction tube are provided in the reaction tube.
 27. Amethanol synthesis system according to claim 1 making use of biomass andequipped with a biomass gasification furnace, wherein the methanolsynthesis unit comprises a pressurizing chamber, a catalyst chamber, anda methanol recovery chamber, and operates such that the synthesis gasintroduced from the biomass gasification furnace into the pressurizingchamber, the catalyst chamber, and the methanol recovery chamber ispressurized at a predetermined pressure, the synthesis gas istransformed into methanol through catalytic reaction in the catalystchamber, the methanol is liquefied in the methanol recovery chamber, andthe liquefied methanol is recovered and the residual gas is purged. 28.A methanol synthesis system making use of biomass according to claim 1,wherein the gasification furnace for gasifying biomass comprises acombustor and a reductor; and coal micropowder is fed to the combustorand the reductor, and biomass is fed to a reductor of the gasificationfurnace or to a site on the downstream side of the reductor, to therebyeffect gasification of the coal and gasification of the biomasssimultaneously.
 29. A methanol synthesis system making use of biomassaccording to claim 28, further comprising a steam reforming means forreforming hydrocarbons contained in the produced gas into CO and H₂, thereforming means being provided within a gasification furnace or at anoutlet of the gasification furnace.
 30. A methanol synthesis systemmaking use of biomass according to claim 28, further comprising a COshift reaction unit for regulating the compositional ratio of H₂ to COgas contained in the purified gas.
 31. A methanol synthesis systemmaking use of biomass according to claim 28, further comprising, on theupstream side of the methanol synthesis unit, a carbon dioxide removingunit for removing CO₂ in the produced gas.
 32. A methanol synthesissystem making use of biomass, characterized in that the feeding meansfor feeding biomass into the biomass gasification furnace as describedin claim 1 comprises: a hollow cylindrical hopper for storing granularmaterial, such as fibrous granular biomass obtained by finelypulverizing biomass, a screw feeder disposed at a lower portion of thehopper and adapted to convey the granular material in a horizontaldirection and to discharge the granular material to the outside throughan outlet which is provided at a distal end portion of a casing of thescrew feeder such that the outlet is opened downward, and stirring meansfor stirring the granular material contained in the hopper such that thegranular material stored in the hopper is fed to the screw feeder.
 33. Amethanol synthesis system making use of biomass according to claim 32,wherein a large-diameter portion having a size larger than that of theremaining portion is provided at a distal end portion of the casingalong the axial direction of the screw feeder, and the outlet isprovided on a lower surface of the large-diameter portion.
 34. Amethanol synthesis system making use of biomass according to claim 32,wherein a plurality of injection nozzles are radially provided at adistal end portion of the casing, and gas is injected through thenozzles to the granular material which has arrived as conveyed whilebeing compressed and constrained between adjacent walls of the screwflight of the screw feeder, to thereby eliminate compression andentanglement of the granular material and discharge the granularmaterial downward through the outlet.
 35. A methanol synthesis systemmaking use of biomass according to claim 32, wherein a screw shaft ofthe screw feeder is formed of a hollow member, and a perforationpenetrating the screw shaft from the outer circumferential surface tothe interior thereof, or an injection nozzle utilizing the perforation,is provided between adjacent walls of the screw flight in the vicinityof a distal end portion of the screw feeder, and gas is injected throughthe perforation or injection nozzle to the granular material which hasarrived as conveyed while being compressed and constrained betweenadjacent walls of the screw flight, to thereby eliminate compression andentanglement of the granular material and discharge the granularmaterial downward through the outlet.
 36. A methanol synthesis systemmaking use of biomass according to claim 32, wherein relatively largepitches are provided between adjacent walls of the screw flight at adistal end portion of the screw shaft of the screw feeder, andrelatively small pitches are provided between adjacent walls of thescrew flight at a central portion of the screw shaft, the centralportion being adjacent to the distal end portion.
 37. A methanolsynthesis system making use of biomass according to claim 32, whereinpitches between adjacent walls of the screw flight of the screw shaft ofthe screw feeder are gradually reduced from the base portion on thehopper side to an intermediate portion at which the pitches are minimum,and the pitches are gradually increased from the intermediate portion tothe distal end portion.